Merge branch 'cursor/pip-keep-alive-2b89' into feature/polish-style-packs

Resolve conflicts in CHANGELOG (keep both entries) and FlowSessionManager
(utterance PCM snapshot + PiP capture release after drain).

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

CHANGELOG.md

@@ -16,6 +16,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 - **Polish style packs**: choose a complete writing personality from the new iOS tab or Mac sidebar, create custom prompts, and sync selections and custom styles through iCloud. / **润色风格包**：可在 iOS 新 Tab 或 Mac 侧栏选择完整写作人格、创建自定义提示词，并通过 iCloud 同步选择与自定义风格。
+- **PiP Flow keep-alive**: Settings → Voice session lets you choose **Dynamic Island** (default, unchanged behaviour) or **Picture in Picture** — a live waveform PiP keeps the host alive with the mic released between utterances; closing PiP ends the session. / **PiP Flow 保活**：设置 → 语音会话可选 **灵动岛**（默认，行为不变）或 **画中画** — 实时波形 PiP 保活、句间释麦；关闭 PiP 即结束会话。
 - **Mac MLX streaming ASR**: local dictation uses Qwen3-ASR via mlx-audio-swift with overlay partial preview, tail drain, vocabulary prompt, and polish-before-insert. / **Mac MLX 流式 ASR**：本地听写改用 mlx-audio-swift 的 Qwen3-ASR，支持浮层 partial 预览、尾部截断、词库 prompt 与润色后再插入。
 
 ### Changed