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

README_EN.md

@@ -56,7 +56,8 @@
 
 **✨ New features**
 
-- 🖼️ **Unified panel-host injection refactor** ([#232](https://github.com/omdsh-dev/DSH-better-sidebar/pull/232)): panels/toggle clusters moved into a `[data-dsh-panel-host]` fixed containing block (`fixed inset-0 z-40`), immune to desktop-shell intermediate transforms hijacking `fixed`; mount self-check (page-level transform → `data-dsh-panel-host-degraded` degraded sync, judged on uncorrected geometry, exits only when the ancestor transform is gone); push anchor switched to `#root [data-dsh-frame] > [data-pane="conversation"]` + `#root` calc width against desktop-shell additive overflow; chunk revalidation on activation (HEAD+ETag keeps unchanged chunks, 5s timeout fails open); desktop signal auto-detection (win32 advanced title-bar compat 32px avoidance, manual pref overrides); `visualViewport` keyboard inset + `env(safe-area-inset-*)` mobile adaptation
+- 🧩 **Desktop compatibility in four options**: "Position compatibility mode" is now a main-row dropdown — **Auto-detect** (default, conservative: only the standard Window Controls Overlay geometry contributes; real 32/36px caption-overlay heights per shell, live on maximize/restore; zero modification on plain web) / **DSH official web** (explicitly no adaptation) / **Shell preset** (built-in, opt-in; only shells that appeared in this repo's issues/PRs with 100+ stars, "detected" badge when the environment matches) / **Custom** (free-form CSS + shift distance, keeps the settings button). Documents that already carried compatibility values migrate to the custom scheme. The core no longer branches per shell; interactive chrome opts out of desktop drag regions (`no-drag`, absorbing #111/#153); the bottom-push anchor is a composite selector (`[data-pane]` and `:has(> [data-slot])` — same element, double protection)
+- 🖼️ **Unified panel-host injection refactor** ([#232](https://github.com/omdsh-dev/DSH-better-sidebar/pull/232)): panels/toggle clusters moved into a `[data-dsh-panel-host]` fixed containing block (`fixed inset-0 z-40`), immune to desktop-shell intermediate transforms hijacking `fixed`; mount self-check (page-level transform → `data-dsh-panel-host-degraded` degraded sync, judged on uncorrected geometry, exits only when the ancestor transform is gone); push anchor switched to `#root [data-dsh-frame] > [data-pane="conversation"]` + `#root` calc width against desktop-shell additive overflow; chunk revalidation on activation (HEAD+ETag keeps unchanged chunks, 5s timeout fails open); `visualViewport` keyboard inset + `env(safe-area-inset-*)` mobile adaptation
 - 📂 **Separate file windows by default** ([#232](https://github.com/omdsh-dev/DSH-better-sidebar/pull/232)): `editorExplorer` now defaults to **separate** — tree clicks / file opens create a new tab per path and the path-less window is a pure file manager; merged mode stays available as an opt-in
 - 🖥️ **Terminal shell / shellArgs configurable from the settings page** ([#232](https://github.com/omdsh-dev/DSH-better-sidebar/pull/232)): the terminal card's gear popup gains "Shell path" and "Shell arguments" rows (previously yaml-only via `cordis.patch.yml`) — saved values take effect immediately for terminals opened afterwards (UI terminals and model `terminal_create` alike); empty keeps the existing yaml → `$SHELL` / login shell / `powershell.exe` resolution order
 - 🏷️ **Version badge on the settings page** ([#232](https://github.com/omdsh-dev/DSH-better-sidebar/pull/232)): the side-card settings section now opens with a `DSH-better-sidebar v0.14.0` identity badge (version synced with the service instance, test-guarded)