fix: Phase 2 QA — all 25 remaining HIGH/MEDIUM/LOW issues

HIGH fixes (7):
- H1: VNCdirectory admin i18n — 30+ translation keys added
- H2: handleSave try/catch with error toast
- H3: Free/busy accountId scoping
- H4: cancelEventBookings filter by eventId
- H5: Resource picker static apiFetch import
- H6: Sharing-store toast messages via lastMessage state
- H7: roleLabel for all resource types

MEDIUM fixes (11):
- M1: identitySignatureMap cleanup on delete
- M2: Now-line relative positioning
- M3: Radial menu disabled item keyboard nav
- M4: Radial menu stable event listener via refs
- M5: cancelBooking error on missing booking
- M6: PasswordRow isMasked state flag
- M7: Extract shared rights into lib/sharing-rights.ts
- M8: VNCtalk client server-side guard
- M9: Collabora configManager instead of process.env
- M10: CONFIG_ENV_MAP VNCdirectory fields
- M11: SENSITIVE_CONFIG_KEYS field name unification

LOW fixes (7):
- L1-L3: Unused imports removed
- L4: aria-labels on close, clear, search, spinner
- L5-L7: Comments for intentional patterns, null guard

lib/demo/demo-client.ts

@@ -888,16 +888,17 @@ export class DemoJMAPClient implements IJMAPClient {
     return { destroyed: eventIds, notDestroyed: [] };
   }
 
-  async queryCalendarEvents(filter: CalendarEventFilter): Promise<CalendarEvent[]> {
-    return this.data.calendarEvents.filter(e => {
+  async queryCalendarEvents(filter: CalendarEventFilter, sort?: Array<{ property: string; isAscending: boolean }>, limit?: number): Promise<CalendarEvent[]> {
+    const events = this.data.calendarEvents.filter(e => {
       if (filter.after && e.start < filter.after) return false;
       if (filter.before && e.start > filter.before) return false;
       return true;
     });
+    return limit ? events.slice(0, limit) : events;
   }
 
-  async queryAllCalendarEvents(filter: CalendarEventFilter): Promise<CalendarEvent[]> {
-    return this.queryCalendarEvents(filter);
+  async queryAllCalendarEvents(filter: CalendarEventFilter, sort?: Array<{ property: string; isAscending: boolean }>, limit?: number): Promise<CalendarEvent[]> {
+    return this.queryCalendarEvents(filter, sort, limit);
   }
 
   async parseCalendarEvents(): Promise<Partial<CalendarEvent>[]> {