fix: resolve all 69 ESLint warnings across 40 files

- Remove unused imports (Mail, CalendarIcon, Plus, Circle, cn, Link,
  MessageCircle, User, Tag, FolderUp, useEffect, LogOut, GripVertical,
  Check, X, HoverActionsMode, HoverActionsCorner, asn1js, Convert, etc.)
- Prefix unused variables/params with underscore to satisfy no-unused-vars
- Add missing React hook dependencies (exhaustive-deps)
- Wrap handleNavigateUp in useCallback and selectedGroupMembers in useMemo
- Remove unused eslint-disable directives in jmap/client.ts
- Replace as any with typed casts in filter-store and smime-store tests
- Remove dead code (macOk assignment, unused now variable)

hooks/use-calendar-alerts.ts

@@ -108,7 +108,7 @@ export function useCalendarAlerts() {
   }, [
     calendarNotificationsEnabled, calendarNotificationSound, notificationSoundChoice,
     isAuthenticated, events, calendars, acknowledgedAlerts,
-    acknowledgeAlert, addToast, t, locale,
+    acknowledgeAlert, addToast, t, locale, enableCalendarTasks, storeTasks,
   ]);
 
   const proactiveFetch = useCallback(async () => {