feat(desktop): two-way cloud sync with mobile and web

Rewrites the desktop mirror as services/sync/SyncEngine: a persistent
outbox, per-account server-clock keyset cursors with paging, pulls that never
overwrite unsent local edits, deletions both ways through sync_tombstones and
per-row failure isolation. It now covers history titles and favorites,
dictionary, every meeting's memos and documents, memo tags, user commands and
dictation/meeting templates, and registers the desktop as a device that the
phone can disconnect.

Fixes shipped defects: the first pull after sign-in fetched nothing, only
the first meeting's children were pushed, team meetings leaked into the
personal database and lost team_id on re-push, and Realtime never connected
because Electron's Node 20 has no global WebSocket (ws is now the transport).
Anonymous local-mode records are imported into the first account that signs
in. The settings sync section is translated and shows pending/rejected
changes; synced screens reload on app:dataChanged.

apps/desktop/src/preload/index.ts

@@ -66,6 +66,7 @@ import type {
   HistoryEntry,
   HistoryDeleteParams,
   HistorySearchParams,
+  HistorySetFavoriteParams,
   DictionaryQueryParams,
   DictionaryPage,
   DictionaryEntry,
@@ -408,6 +409,8 @@ const electronAPI = {
     delete: (params: HistoryDeleteParams) =>
       invoke<void>(IPC_CHANNELS.HISTORY.DELETE, params),
     deleteAll: () => invoke<void>(IPC_CHANNELS.HISTORY.DELETE_ALL),
+    setFavorite: (params: HistorySetFavoriteParams) =>
+      invoke<HistoryEntry>(IPC_CHANNELS.HISTORY.SET_FAVORITE, params),
     search: (params: HistorySearchParams) =>
       invoke<HistoryPage>(IPC_CHANNELS.HISTORY.SEARCH, params),
     onAdded: (cb: (e: HistoryEntry) => void): Unsubscribe =>
@@ -469,8 +472,13 @@ const electronAPI = {
 
   // ── App 이벤트 (실시간 UI 갱신) ────────────────────────
   app: {
-    onDataChanged: (cb: (data: { type: string; activeId?: string }) => void): Unsubscribe =>
-      on('app:dataChanged', cb),
+    /**
+     * 로컬 데이터가 바뀌었다 — 화면을 다시 불러온다.
+     * type 'cloud-sync'는 다른 기기(모바일·웹)의 변경이 반영된 것이고 entities에 바뀐 종류가 온다.
+     */
+    onDataChanged: (
+      cb: (data: { type: string; activeId?: string; entities?: string[] }) => void
+    ): Unsubscribe => on(IPC_CHANNELS.APP.DATA_CHANGED, cb),
   },
 
   // ── Phase 10: Memo Tags ─────────────────────────────────
@@ -802,6 +810,8 @@ const electronAPI = {
         userEmail: string | null
         lastSyncAt: number | null
         syncing: boolean
+        pendingChanges: number
+        failedChanges: number
       }>(IPC_CHANNELS.CLOUD_SYNC.GET_STATE),
     signIn: (params: { provider: 'google' | 'github' }) =>
       invoke<{ started: boolean }>(IPC_CHANNELS.CLOUD_SYNC.SIGN_IN, params),