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/ja.json

@@ -541,5 +541,10 @@
   "cloudSync.browserPending": "ブラウザでログインを完了してください。",
   "cloudSync.signedOut": "ログアウトしました。このコンピューターの記録はそのまま残ります。",
   "cloudSync.done": "同期完了（{{count}} 件反映）",
-  "cloudSync.doneWithErrors": "同期完了（{{count}} 件反映、{{errors}} 件失敗 — 次回の同期で再試行）"
+  "cloudSync.doneWithErrors": "同期完了（{{count}} 件反映、{{errors}} 件失敗 — 次回の同期で再試行）",
+  "history.playAudio": "録音を再生",
+  "history.stopAudio": "再生を停止",
+  "history.audioUnavailable": "再生できる録音がありません（他の端末の録音は、その端末の同期後に再生できます）",
+  "cloudSync.audio": "録音ファイルも同期",
+  "cloudSync.audioDesc": "録音をクラウドにアップロードし、モバイルやウェブで再生できるようにします。50MBを超えるファイルはこのコンピューターにのみ保存されます。"
 }