fix(mac): prevent Option release deadlock and HUD layout storm

The hold-to-talk release path called AsyncStream.Continuation.finish()
while holding MacAudioRecorder's NSLock; onTermination re-entered the
same lock on the main thread and froze the app. Finish snapshot sinks
outside the lock and guard the audio tap once stop() begins.

The dictation HUD no longer reassigns its hosting view and forces a
synchronous relayout on every view-model tick; it uses a fixed panel
size and SwiftUI @ObservedObject refresh instead.

Adds OSGKeyboardMacTests with a regression test that fails under the
old lock re-entry pattern.

CHANGELOG.md

@@ -16,6 +16,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - **Mac Settings translation target**: polish-provider section includes “Polish then translate” with the same locale picker as Home / menu bar. / **Mac 设置翻译目标**：润色（LLM）分区新增「润色后翻译」，与首页 / 菜单栏同一套目标语言选择。
 
 ### Fixed
+- **macOS Option release freeze**: finishing a live snapshot stream no longer calls `AsyncStream.Continuation.finish()` while holding the recorder lock — the termination handler re-entered the same `NSLock` on the main thread and wedged the app when the hold-to-talk key was released. / **macOS 松开 Option 卡死**：结束实时 snapshot 流时不再在持有 recorder 锁的情况下调用 `AsyncStream.Continuation.finish()`；终止回调会在主线程重入同一把 `NSLock`，松开听写键时导致整个 App 无响应。
+- **macOS dictation HUD layout storm**: the floating pill no longer reassigns its hosting view and forces a synchronous relayout on every view-model tick (~20×/s from the level timer); it uses a fixed panel size and lets SwiftUI refresh through `@ObservedObject` instead. / **macOS 听写浮层布局风暴**：悬浮胶囊不再在每次 view-model 更新时重建 hosting 视图并强制同步重排（音量定时器约 20 次/秒）；改为固定面板尺寸，由 SwiftUI `@ObservedObject` 驱动刷新。
 - **Polish never answers the transcript**: fun styles (dating / flex / corp) could turn “你觉得这个包怎么样” into a reply such as “还行，挺顺眼的”. A top-priority “polish only, never answer” rule now sits in the global contract, every built-in style pack, the prompt safety boundary, and a router question guard that keeps question drafts as questions. / **润色不再代答转写内容**：趣味风格（直男癌/装逼指南/大厂黑话）曾把「你觉得这个包怎么样」润色成「还行，挺顺眼的」。现已在全局契约、全部内置风格包、提示词安全边界与路由问句守卫四层加入最高优先级的「只润色、不作答」规则，问句必须仍是问句。
 
 ### Changed