feat(dsh): adapt to DSH 0.1.5-rc.1 and restore the guide description

Baseline moves to DSH 0.1.5-rc.1 — the 0.1.5 line's first release
candidate, and the npm `latest` dist-tag now: peer floor ^0.1.5-rc.1,
devDependency pins, the CI mount-lane pin and dsh.plugin.json engines
all follow. 0.1.5-alpha.2 users stay on v0.19.0-alpha.1.

The upstream delta from alpha.2 is small: 373 changed files, mostly
version bumps, sidebar preview polish and test snapshots. Exactly two
changes touch this plugin, and only one needs work:

- `SidebarRightGuideEntry.description` is back (optional). The native
  guide renders it only while it lists at most 4 entries; a longer list
  drops every description. The plugin restores `TabDescriptor.description`
  and the six built-in `guideDesc*` lines (20 dictionaries) verbatim from
  0b6ac5d^, but deliberately does NOT restore the old generic
  `nativeGuideDesc` fallback: the host has no fallback of its own, so a
  descriptor that declares none now ships no `description` field at all
  and renders as a clean title-only capsule.

  Consequence worth knowing: the plugin contributes six guide entries, so
  the default composition is over the 4-entry limit and shows titles only.
  The mount lane proves the restored field end to end by shrinking the
  enabled set to three types through the plugin's own settings route
  (scratch profile only) and requiring the Files capsule to grow its line.

- The built-in `files` type declares a guide description again and uses a
  coloured folder glyph; the plugin owns that kind, so nothing to do.

Verified unchanged from alpha.2 (so nobody re-checks them): the global
main-panel model, the file address grammar (util/workspace-path changed
only its package.json), the native tab-body host contract (.paneBody is
still a block scroller with a definite height), the core/agent/session/
subagent host APIs and the ui-primitives export surface.

Restore caveat fixed in the lane: the settings route merges patches
key-wise, so undoing a temporary `tabsEnabled` change by posting the
original (empty) map leaves the disabled keys behind — the e2e restores
every key it touched explicitly.

src/client/locales.ts

@@ -24,6 +24,12 @@
 /** The zh dictionary (also registered into the DSH locale registry under {@link LOCALE_NS}). */
 export const zh = {
   files: '文件',
+  guideDescFiles: '浏览工作区文件树，点开即预览或编辑',
+  guideDescGit: 'Git 变更与本轮文件改动，双视角合一',
+  guideDescSubagent: '子代理拓扑与后台任务，实时状态',
+  guideDescSidechat: '继承当前会话上下文的独立追问线程',
+  guideDescTerminal: '真实 shell 终端（xterm + pty），断线重连',
+  guideDescBrowser: '内嵌网页浏览器，可接管聊天里的外链',
   changesSessionEmpty: '本会话还没有文件操作',
   changesRead: '读取',
   changesMdReading: '阅读',
@@ -458,6 +464,12 @@ export const zh = {
 /** The en dictionary (key-set-equal to zh, enforced by the type annotation). */
 export const en: Record<keyof typeof zh, string> = {
   files: 'Files',
+  guideDescFiles: 'Browse the workspace tree; click a file to preview or edit',
+  guideDescGit: 'Git changes and this session\'s file edits, in one tab',
+  guideDescSubagent: 'Subagent topology and background jobs, live',
+  guideDescSidechat: 'An independent follow-up thread inheriting this session\'s context',
+  guideDescTerminal: 'A real shell (xterm + pty) with reconnect',
+  guideDescBrowser: 'An embedded browser that can take over chat links',
   changesSessionEmpty: 'No file operations in this session yet',
   changesRead: 'Read',
   changesMdReading: 'Reading',