feat(sidebar): 桌面兼容三方案——自动检测(WCO 标准几何)/壳预设/自定义 CSS (#284)

* feat(sidebar): 桌面兼容三方案——自动检测(WCO 标准几何)/壳预设/自定义 CSS

核心只保留 Web 标准机制，壳专属适配全部下沉到用户空间（KISS）：
- prefs 新增 titleBarScheme(默认 auto)/titleBarPresetId/customCss，旧 titleBarCompat
  布尔自动迁移（true→custom 保留 stripPx，false/缺失→auto）
- wco.ts：navigator.windowControlsOverlay 反应式几何（geometrychange 实时更新；
  visible=false 的幽灵 API 视为缺失），实现 #257
- titlebar-strip.ts 唯一 strip 取值链：WCO → dsh-desktop-titlebar-inset 契约参数
  → 预设 stripFor → 手动 px → 0；desktop-env.ts 移除 win32 32px 硬编码
- shell-presets.ts 数据驱动预设（准入：issue/PR 提及 + 100+ star；v1 仅
  anywhere-labs DSH Desktop：darwin 20px / win32 无 WCO 时 32px），opt-in 手动
- 预设/自定义 CSS 注入（data-dsh-preset-css / data-dsh-custom-css 标签），
  chrome 补稳定寻址面 data-dsh-toggle-cluster / data-dsh-panel
- 交互 chrome 统一 -webkit-app-region: no-drag（吸收 #111/#153）
- layout.css 底栏推挤复合锚点（[data-pane] 与 :has(> [data-slot]) 双保险，
  rc.8 实测前者失效、后者命中，吸收 #226 思路）
- 设置 UI：位置兼容模式齿轮弹窗改三方案（自动检测/壳兼容方案/自定义方案）
- 测试：wco/titlebar-strip/shell-presets 单测 + prefs 迁移 + e2e 5 场景
  （保守 auto/WCO 反应式/预设/自定义 CSS/复合锚点），挂载门禁 12/12 全绿

核心 grep 无壳专属类名；为某壳做的兼容在另一壳会再坏——预设与自定义 CSS
是唯一出路（AGENTS.md §8 契约已更新）。

* refine(sidebar): 位置兼容模式改主行下拉四选项——自动检测/DSH官方Web/壳预设/自定义

按用户反馈定稿 UI：
- 主行下拉：自动检测（默认）/ DSH官方Web（显式零适配，连 WCO 也强制 0）/
  各壳预设（命中环境带「已检测」后缀，仅提示）/ 自定义方案（保留齿轮弹窗：
  下移距离 + 自定义 CSS）
- 旧文档迁移：titleBarCompat=true 或 titleBarStripPx 非默认值（此前已有配置）
  → 默认落到 custom 方案保留用户数值；干净文档 → auto
- prefs 新增 'web' 方案；strip 取值链最优先处理 web→0
- 测试：prefs 迁移（stripPx 48→custom / 40→auto）、web 强制 0、下拉渲染断言
- 单测 693 通过，挂载 e2e 12/12 全绿

* refine(sidebar): 方案下拉复用 SelectMenu 组件，不用原生 <select>

- 抽出可复用 SelectMenu（primitives Menu：锚点按钮 + 下拉选项卡，支持
  icon/desc/多选），SelectRow 改为其薄壳
- 位置兼容模式方案下拉改用 SelectMenu；选项带描述（自动检测/DSH官方Web/
  各壳预设(命中带「已检测」后缀)/自定义方案）
- 移除原生 select 样式；单测 693 通过，挂载 e2e 12/12 全绿

src/client/shell-presets.ts

@@ -0,0 +1,83 @@
+/**
+ * Built-in desktop-shell presets for the "位置兼容模式" secondary setting
+ * (scheme `preset`). DATA-DRIVEN by design: each shell's adaptation lives
+ * in one entry (strip values / optional CSS), the core applies it through
+ * the SAME generic strip variable and CSS-injection mechanism — adding a
+ * shell is adding data, never a code path.
+ *
+ * Inclusion rule (maintained in AGENTS.md §8): only shells that (a) appear
+ * in this repo's issues/PRs (a user actually hit a problem) and (b) have
+ * 100+ GitHub stars (a real user base). The mechanism is opt-in: auto
+ * detection never applies a preset — the settings badge only SUGGESTS it.
+ */
+import type { DesktopEnv } from './desktop-env.ts'
+
+export interface ShellPreset {
+  /** Stable preset id (persisted in `titleBarPresetId`). */
+  readonly id: string
+  /** User-facing name of the shell. */
+  readonly title: string
+  /** One-line description shown in the settings popup. */
+  readonly desc: string
+  /**
+   * The top strip (px) this shell reserves over web content, per
+   * environment — the fallback used when neither the standard WCO API nor
+   * the `dsh-desktop-titlebar-inset` contract parameter is available.
+   * Return undefined when the shell needs no strip in that environment.
+   * MUST be pure (called during render).
+   */
+  readonly stripFor?: (env: DesktopEnv) => number | undefined
+  /**
+   * Extra CSS applied while the preset is enabled (injected last, after the
+   * plugin's own styles). Targets the plugin's stable data attributes and
+   * shell-declared body/URL markers only — never other shells' class names.
+   * Empty for presets fully covered by the strip variable.
+   */
+  readonly css?: string
+  /**
+   * Whether this shell's marker is currently visible (URL stamps / preload
+   * markers — see desktop-env.ts). Used ONLY for the settings "已检测"
+   * badge; never auto-applies anything. MUST be pure.
+   */
+  readonly detect?: (env: DesktopEnv) => boolean
+}
+
+/**
+ * DeepSeek Harness Desktop (anywhere-labs, Electron, 16k+ stars — the most
+ * reported shell in this repo's issues/PRs). Advanced mode: macOS reserves
+ * a 20px caption row (traffic lights top-left), win32 draws the native
+ * window controls in a ~32px overlay (WCO reports the real height when
+ * available, which the auto scheme already consumes; the 32 is the
+ * no-WCO fallback). Compatibility mode keeps the native frame — nothing.
+ */
+const DSH_DESKTOP: ShellPreset = {
+  id: 'dsh-desktop',
+  title: 'DeepSeek Harness Desktop',
+  desc: 'Electron 高级模式（无边框）：macOS 顶栏 20px、Windows 无 WCO 时 32px 标题栏让位',
+  stripFor: (env) => {
+    if (env.mode !== 'advanced') return undefined
+    if (env.platform === 'darwin') return 20
+    if (env.platform === 'win32') return 32
+    return undefined
+  },
+  detect: (env) => env.mode === 'advanced',
+}
+
+const PRESETS: readonly ShellPreset[] = [
+  DSH_DESKTOP,
+]
+
+/** All built-in shell presets (registration order = settings list order). */
+export function getShellPresets(): readonly ShellPreset[] {
+  return PRESETS
+}
+
+/** One preset by id, or undefined for an unknown/empty id. */
+export function getShellPreset(id: string): ShellPreset | undefined {
+  return PRESETS.find(preset => preset.id === id)
+}
+
+/** The strip the active preset contributes for the given environment. */
+export function presetStripFor(preset: ShellPreset | undefined, env: DesktopEnv): number | undefined {
+  return preset?.stripFor?.(env)
+}