fix: Phase 1 critical+high fixes (17/18 items)

CRITICAL fixes:
- C1: Error swallowing - throw TransportError on network failure in getEmails/searchEmails
- C2: Recurrence expansion ID delimiter changed from ':' to '::occurrence::'
- C3: Cross-account calendar event UID dedup after multi-account aggregation
- C4: Admin session token revocation via JTI blacklist on logout
- C6: FTS5 schema-drop - add warning log for automatic reindex trigger
- C7: Settings lock - gate updateSetting() with isSettingLocked() check
- C8: Offline push pause - add offline event handler that closes push transports

HIGH fixes:
- H1: Push handler - add ContactCard and FileNode branches
- H2: WS fallback - await state snapshot before reconcileAfterWebSocketFallback
- H3: Auth rate limiting - add checkUserAuthRateLimit to session and token routes
- H4: OAuth logs - strip access_token from error log context
- H7: Template XSS - apply DOMPurify to HTML template body on import
- H8: Secure cookie - derive from x-forwarded-proto, not NODE_ENV
- H9: bcrypt fix - remove bcrypt prefixes from isHashed() so scrypt-only
- H13: calendarTasksEnabled - apply admin gate at runtime in calendar page
- H14: Task mutations - add try/catch error handling to update/delete/toggle
- H18: autoSelectReplyIdentity default changed from false to true

Deferred: P1.3 (C5 auth localStorage encryption) - requires custom Zustand persist adapter.

stores/task-store.ts

@@ -65,30 +65,45 @@ export const useTaskStore = create<TaskStore>((set, get) => ({
   },
 
   updateTask: async (client, id, updates) => {
-    await client.updateCalendarTask(id, updates);
-    set({
-      tasks: get().tasks.map(t => t.id === id ? { ...t, ...updates, updated: new Date().toISOString() } : t),
-    });
+    try {
+      await client.updateCalendarTask(id, updates);
+      set({
+        tasks: get().tasks.map(t => t.id === id ? { ...t, ...updates, updated: new Date().toISOString() } : t),
+      });
+    } catch (error) {
+      debug.error('TaskStore/updateTask failed', error);
+      set({ error: 'Failed to update task' });
+    }
   },
 
   deleteTask: async (client, id) => {
-    await client.deleteCalendarTask(id);
-    set({
-      tasks: get().tasks.filter(t => t.id !== id),
-      selectedTaskId: get().selectedTaskId === id ? null : get().selectedTaskId,
-    });
+    try {
+      await client.deleteCalendarTask(id);
+      set({
+        tasks: get().tasks.filter(t => t.id !== id),
+        selectedTaskId: get().selectedTaskId === id ? null : get().selectedTaskId,
+      });
+    } catch (error) {
+      debug.error('TaskStore/deleteTask failed', error);
+      set({ error: 'Failed to delete task' });
+    }
   },
 
   toggleTaskComplete: async (client, task) => {
-    const newProgress = task.progress === 'completed' ? 'needs-action' : 'completed';
-    const updates: Partial<CalendarTask> = {
-      progress: newProgress,
-      progressUpdated: new Date().toISOString(),
-    };
-    await client.updateCalendarTask(task.id, updates);
-    set({
-      tasks: get().tasks.map(t => t.id === task.id ? { ...t, ...updates, updated: new Date().toISOString() } : t),
-    });
+    try {
+      const newProgress = task.progress === 'completed' ? 'needs-action' : 'completed';
+      const updates: Partial<CalendarTask> = {
+        progress: newProgress,
+        progressUpdated: new Date().toISOString(),
+      };
+      await client.updateCalendarTask(task.id, updates);
+      set({
+        tasks: get().tasks.map(t => t.id === task.id ? { ...t, ...updates, updated: new Date().toISOString() } : t),
+      });
+    } catch (error) {
+      debug.error('TaskStore/toggleTaskComplete failed', error);
+      set({ error: 'Failed to update task' });
+    }
   },
 
   clearTasks: () => set({ tasks: [], selectedTaskId: null, error: null }),