feat(desktop): sync knowledge, recordings and shared settings; play any recording

Knowledge documents travel as source-text chunks; each surface embeds them
with its own model, the server index is requested through embed-chunks, and
documents from the phone are stored without a file and indexed from their
chunks. Chunk text is now kept when local embedding fails, so reindexing no
longer needs the original file.

Recordings upload to the mobile storage contract (audio bucket under the
user's folder plus an audio_files row, 50 MiB cap, a Settings > Cloud
toggle) and are removed with their record. The history card gains a play
button that uses the local file or, for phone recordings, a signed URL.

Language (ko/en), system/light/dark theme, auto-polish and the active user
command follow the phone's user_settings with its revision rule; changes that
arrive from the phone reach the open window.

packages/i18n/src/locales/ko.json

@@ -1934,5 +1934,10 @@
   "mobile.devices.platform.ios": "iPhone·iPad",
   "mobile.devices.platform.web": "웹 브라우저",
   "mobile.devices.platform.windows": "Windows 데스크톱 앱",
-  "mobile.devices.platform.macos": "macOS 데스크톱 앱"
+  "mobile.devices.platform.macos": "macOS 데스크톱 앱",
+  "history.playAudio": "녹음 듣기",
+  "history.stopAudio": "재생 멈춤",
+  "history.audioUnavailable": "들을 수 있는 녹음이 없습니다 (다른 기기 녹음은 그 기기의 동기화가 끝나면 들을 수 있어요)",
+  "cloudSync.audio": "녹음 파일도 동기화",
+  "cloudSync.audioDesc": "녹음을 클라우드에 올려 모바일·웹에서 들을 수 있게 합니다. 50MB를 넘는 파일은 이 컴퓨터에만 둡니다."
 }