feat(flow): implement ABCD session policy and host return whitelist

- Scheme A: on-demand session start, inactivity-based expiry, handoff auto-recording
- Scheme B: cold-start overlay with swipe guidance and return alert
- Scheme C+D: HostAppURLRegistry (20 apps) and sourceApplication capture
- Settings: skip app switch toggle and inactivity duration picker
- Add LSApplicationQueriesSchemes for canOpenURL checks

Co-authored-by: Rocky <hkgood@users.noreply.github.com>

CHANGELOG.md

@@ -10,8 +10,12 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Added
 - **Flow Live Activity**: Dynamic Island shows the OSGKeyboard brand mark during an active voice session (ActivityKit widget extension). / **Flow 灵动岛 Live Activity**：语音会话期间在灵动岛显示 OSGKeyboard 品牌标识（ActivityKit 小组件扩展）。
 - **Xiaomi MiMo cloud provider**: preset for the cloud engine with `mimo-v2.5` polish via `api.xiaomimimo.com` (on-device ASR, same pipeline as other online providers). / **小米 MiMo 云端引擎**：云端引擎新增预设，经 `api.xiaomimimo.com` 使用 `mimo-v2.5` 润色（端侧 ASR，与其他在线服务相同管线）。
+- **Flow session policy (A)**: on-demand session start from the keyboard; inactivity-based expiry (10m–24h, default 12h) reset after each utterance; handoff auto-starts recording. / **Flow 会话策略（A）**：键盘按需启动会话；无活动超时（10 分钟–24 小时，默认 12 小时）每句结束后重置；交接完成后自动开始录音。
+- **Skip app switch (B+C)**: settings toggle (default on) plus cold-start overlay with swipe-back guidance and optional “Return to [App]” alert. / **跳过应用切换（B+C）**：设置开关（默认开）+ 冷启动极简页（右滑引导 + 可选「返回 [App]」弹窗）。
+- **Host return whitelist (C+D)**: `HostAppURLRegistry` with 20 high-frequency host apps; `sourceApplication` capture on `startflow`. / **宿主回跳白名单（C+D）**：`HostAppURLRegistry` 覆盖 20 个高频宿主 App；`startflow` 时记录 `sourceApplication`。
 
 ### Changed
+- **Keyboard language label**: `PrimaryLanguage` set to `mis` so Settings no longer shows a misleading “English” subtitle under OSGKeyboard. / **键盘语言标签**：`PrimaryLanguage` 设为 `mis`，系统设置中 OSGKeyboard 下不再显示误导性的「英文」副标题。
 - **Flow ASR pipelining**: shorter first chunk (2.5s) and 5s follow-ups so short utterances start on-device recognition while still recording; session-level ASR warmup and format cache reuse; live partials mirrored to the keyboard transcript line. / **Flow ASR 流水线**：首块 2.5 秒、后续 5 秒，短句录音期间即开始端侧识别；会话级 ASR 预热与格式缓存复用；实时 partial 同步到键盘转写行。
 
 ## [0.4.0] - 2026-07-05