feat(editor): 文件窗口与资源管理器二合一 + 声明式设置 select 行 (#151)

* feat(editor): merged explorer mode — path input, docked file tree, global name search

New editorExplorer pref (default on, editor card gear): the editor tab gains
a path-input header and a toggleable right-docked tree panel (per-tab state
in tab.meta.treeOpen; file tabs default closed, the seeded path-less home
tab defaults open). Fresh sessions seed that empty editor tab instead of
the explorer tab when merged mode is on; the standalone explorer tab stays
in the + menu unchanged.

- Extract FileTree.tsx from ExplorerView (shared by both hosts)
- Host fs.search route: recursive case-insensitive name search rooted at
  the session cwd, budget-capped (200 matches / 100k visited), skips .git,
  never descends symlink dirs
- EditorHost reads the pref reactively (boolean snapshot) and keeps the
  pre-merge layout verbatim when off

* feat(settings): select row type for declarative settings; editorExplorer as iconed select

- SidebarSettingToggle gains type 'select' with options {value,title,desc,icon}
  and multi (default false; stores the picked values as an array in options
  order). Any option carrying an icon renders big-icon option cards in the
  dropdown and the icon in the closed anchor; icon-less rows are one-line text.
- SelectRow in SideCardSection rides the primitives Menu (portal); single-pick
  commits and closes, multi toggles and stays open. Wired for both host-prefs
  toggles and plugin-owned pluginToggles via the new onSelectValue seam.
- The editorExplorer merged-mode pref is now an iconed select (merged vs
  separate) instead of a switch; the stored value stays boolean.
- Advertise the capability as 'settingSelect' in SIDEBAR_FEATURES.

* feat(editor): unify explorer into the editor surface, resizable tree dock, hoisted toolbar

- One tree implementation, two presentations: the shared TreePanel (global
  name search + refresh + FileTree) docks as the editor tab's right panel
  and — in merged mode — fills the explorer tab's window; the pref-off
  explorer keeps its legacy header shell.
- The docked panel drag-resizes from its left edge (160-480px clamp),
  persisted as tab.meta.treeWidth alongside treeOpen.
- The text editor's preview/edit/save toolbar moves into the path-input
  header row: FileViewerProps gains internal toolbar fields ('host' mode
  skips the viewer's own row, reports EditorToolbarState and registers
  EditorToolbarControls); non-merged mode is byte-identical to before.

* feat(editor): single files window with in-place switching; explorer descriptor removed

- editor tab replaces explorer on the + menu (order 10, Files); persisted
  explorer tabs migrate to the editor home tab via sanitizeState
- editorExplorer now only controls open behavior: merged = in-place
  updateTab, independent = openSidebarFile; both modes share the merged
  chrome (path input + hoisted preview/edit/save toolbar + tree toggle)
- file tree context menu gains 'open in new tab' / 'open to the side'
  (mintTabId avoids the id safety net; insertLeafAt splits right)
- tree dock resize uses pointer capture (touch-action none, 6px handle)
- defaults: openByDefault off, sidebar width 35%
- file tree clips horizontal overflow (no sideways scroll)
- e2e: mount lane arms the editor-chunk wait before goto and clicks the
  tree row's left edge (hover @-reference button sits mid-row); drag lane
  expands the panel first (collapsed push writes 0px), waits for the
  slide-in to settle, and picks the leftmost col-resize strip; 'Files'
  title assertions require draggable to skip the bottom panel's welcome
  cards

* feat(editor): split mode turns the path-less window into the standalone explorer

In independent (split) mode a path-less files window renders ONLY the
tree panel (search + FileTree, full-window form) — no path input, no
hoisted toolbar, no tree toggle. File clicks open per-path editor tabs
(full chrome, tree docked closed by default) through openSidebarFile,
unchanged. Merged mode is untouched (chrome + docked tree, in-place
switching). TreePanel's previously reserved 'full' prop now has its
consumer.

src/client/SideCardSection.tsx

@@ -41,9 +41,11 @@
 import { Fragment, useEffect, useRef, useState, type ReactNode } from 'react'
 import {
   IconCheckOutline16,
+  IconChevronDownOutline14,
   IconPlusOutline16,
   IconSettingsOutline16,
   Input,
+  Menu,
   Modal,
 } from '@deepseek-ai/dsh-client-ui-primitives'
 import clsx from 'clsx'
@@ -209,6 +211,10 @@ export function FeatureSettingsRows(props: {
    *  display (clamped for numbers, the current pref when the input is
    *  invalid). Optional: rows with no handler keep their draft. */
   onCommit?: (toggle: SidebarSettingToggle, raw: string) => string
+  /** Commit one select row: the picked option's value (single) or the array
+   *  of picked values (`multi: true`). Optional: rows with no handler are
+   *  display-only. */
+  onSelectValue?: (toggle: SidebarSettingToggle, next: unknown) => void
   /** Explicit value source (v0.12.0+): when given, rows read their values
    *  from it instead of the `prefs` face — plugin-owned rows read their
    *  own blob, so a plugin key can never collide with (or silently read)
@@ -216,12 +222,23 @@ export function FeatureSettingsRows(props: {
    *  the latter collides with the inherited Object.prototype.valueOf.) */
   valueSource?: (key: string) => unknown
 }) {
-  const { toggles, prefs, onToggle, onCommit, valueSource } = props
+  const { toggles, prefs, onToggle, onCommit, onSelectValue, valueSource } = props
   const read = valueSource ?? ((key: string): unknown => (prefs as unknown as Record<string, unknown>)[key])
   return (
     <div className={css.popupRows}>
       {toggles.map(toggle => {
         const title = textOf(toggle.title)
+        if (toggle.type === 'select') {
+          return (
+            <SelectRow
+              key={toggle.key}
+              toggle={toggle}
+              title={title}
+              value={read(toggle.key)}
+              onSelectValue={onSelectValue}
+            />
+          )
+        }
         if ((toggle.type ?? 'switch') === 'switch') {
           return (
             <div key={toggle.key} className={css.popupRow}>
@@ -302,6 +319,99 @@ function TypedRow(props: {
   )
 }
 
+/**
+ * One select row: a dropdown over the toggle's declared `options`. When any
+ * option carries an icon, the dropdown renders big-icon option cards (icon +
+ * title + desc) and the closed anchor shows the selected option's icon as
+ * well; without icons both are a single line of text. Single-pick commits the
+ * option's value and closes; `multi` toggles membership, commits the picked
+ * values as an array (in options order), and stays open.
+ */
+function SelectRow(props: {
+  toggle: SidebarSettingToggle
+  title: string
+  value: unknown
+  onSelectValue?: (toggle: SidebarSettingToggle, next: unknown) => void
+}) {
+  const { toggle, title, value, onSelectValue } = props
+  const options = toggle.options ?? []
+  const multi = toggle.multi === true
+  const [open, setOpen] = useState(false)
+  const hasIcons = options.some(option => option.icon !== undefined)
+  const picked: readonly unknown[] = multi ? (Array.isArray(value) ? value : []) : [value]
+  const selected = options.filter(option => picked.includes(option.value))
+
+  /** Commit one picked option (toggle semantics under multi). */
+  const pick = (index: number): void => {
+    const option = options[index]
+    if (option === undefined) return
+    if (!multi) {
+      onSelectValue?.(toggle, option.value)
+      setOpen(false)
+      return
+    }
+    const current = Array.isArray(value) ? [...value] : []
+    const at = current.indexOf(option.value)
+    if (at >= 0) current.splice(at, 1)
+    else current.push(option.value)
+    // Stable wire order: follow the declared options order, not pick order.
+    onSelectValue?.(toggle, options.filter(o => current.includes(o.value)).map(o => o.value))
+  }
+
+  const anchor = (
+    <button
+      type="button"
+      className={css.selectAnchor}
+      aria-label={title}
+      aria-haspopup="listbox"
+      aria-expanded={open}
+      onClick={() => { setOpen(now => !now) }}
+    >
+      {!multi && hasIcons && selected[0] !== undefined && (
+        <span className={css.selectAnchorIcon}>{iconOf(selected[0].icon, 16)}</span>
+      )}
+      <span className={css.selectAnchorText}>
+        {selected.length === 0 ? '—' : selected.map(option => textOf(option.title)).join(', ')}
+      </span>
+      <IconChevronDownOutline14 size={12} />
+    </button>
+  )
+
+  return (
+    <div className={css.popupRow}>
+      <span className={css.rowText}>
+        <span className={css.title}>{title}</span>
+        {textOf(toggle.desc) !== '' && <span className={css.desc}>{textOf(toggle.desc)}</span>}
+      </span>
+      <span className={css.control}>
+        <Menu
+          open={open}
+          anchor={anchor}
+          items={options.map((option, index) => ({
+            id: String(index),
+            label: hasIcons
+              ? (
+                <span className={css.selectOption}>
+                  <span className={css.selectOptionIcon}>{iconOf(option.icon, 24)}</span>
+                  <span className={css.selectOptionText}>
+                    <span className={css.title}>{textOf(option.title)}</span>
+                    {textOf(option.desc) !== '' && <span className={css.desc}>{textOf(option.desc)}</span>}
+                  </span>
+                </span>
+              )
+              : textOf(option.title),
+          }))}
+          selectedId={!multi && selected[0] !== undefined ? String(options.indexOf(selected[0])) : undefined}
+          selectedIds={multi ? selected.map(option => String(options.indexOf(option))) : undefined}
+          onSelect={(id) => { pick(Number(id)) }}
+          onClose={() => { setOpen(false) }}
+          portal
+        />
+      </span>
+    </div>
+  )
+}
+
 /**
  * The secondary settings popup body of one feature (tab or viewer):
  * - `settings.render` (custom panel) when declared — rendered with the
@@ -318,12 +428,14 @@ export function SettingsBody(props: {
   service: BetterSidebarService
   onToggle: (toggle: SidebarSettingToggle, next: boolean) => void
   onCommit: (toggle: SidebarSettingToggle, raw: string) => string
+  onSelectValue: (toggle: SidebarSettingToggle, next: unknown) => void
   onPluginToggle: (toggle: SidebarSettingToggle, next: boolean) => void
   onPluginCommit: (toggle: SidebarSettingToggle, raw: string) => string
+  onPluginSelectValue: (toggle: SidebarSettingToggle, next: unknown) => void
   onPluginWrite: (key: string, value: unknown) => void
   onClose: () => void
 }) {
-  const { feature, prefs, store, service, onToggle, onCommit, onPluginToggle, onPluginCommit, onPluginWrite, onClose } = props
+  const { feature, prefs, store, service, onToggle, onCommit, onSelectValue, onPluginToggle, onPluginCommit, onPluginSelectValue, onPluginWrite, onClose } = props
   const render = feature.settings?.render
   if (render !== undefined) {
     return (
@@ -356,6 +468,7 @@ export function SettingsBody(props: {
           prefs={prefs}
           onToggle={onToggle}
           onCommit={onCommit}
+          onSelectValue={onSelectValue}
         />
       )}
       {pluginToggles.length > 0 && (
@@ -364,6 +477,7 @@ export function SettingsBody(props: {
           prefs={prefs}
           onToggle={onPluginToggle}
           onCommit={onPluginCommit}
+          onSelectValue={onPluginSelectValue}
           valueSource={(key) => pluginBlob[key]}
         />
       )}
@@ -493,6 +607,12 @@ export function SideCardSection({ store, service }: SideCardSectionProps) {
     applyPref({ [toggle.key]: next })
   }
 
+  /** Commit one declaratively-declared select row (the option's value, or an
+   *  array of values under `multi`). */
+  const onSelectSetting = (toggle: SidebarSettingToggle, next: unknown): void => {
+    applyPref({ [toggle.key]: next })
+  }
+
   /**
    * Commit one declaratively-declared text/number row. Numbers are parsed
    * and clamped to the toggle's declared min/max (an unparsable input falls
@@ -807,8 +927,10 @@ export function SideCardSection({ store, service }: SideCardSectionProps) {
             prefs={prefs}
             onToggle={onToggleSetting}
             onCommit={onCommitSetting}
+            onSelectValue={onSelectSetting}
             onPluginToggle={(toggle, next) => { onPluginToggle(settingsFor.id, toggle, next) }}
             onPluginCommit={(toggle, raw) => onPluginCommitSetting(settingsFor.id, toggle, raw)}
+            onPluginSelectValue={(toggle, next) => { applyPluginSetting(settingsFor.id, toggle.key, next) }}
             onPluginWrite={(key, value) => { applyPluginSetting(settingsFor.id, key, value) }}
             onClose={() => { setSettingsFor(null) }}
             store={store}