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)

app/[locale]/calendar/page.tsx

@@ -186,7 +186,7 @@ export default function CalendarPage() {
     if (client && enableCalendarTasks && (normalizedViewMode === "tasks" || showTasksOnCalendar)) {
       taskStore.fetchTasks(client);
     }
-  }, [client, enableCalendarTasks, normalizedViewMode, showTasksOnCalendar]);
+  }, [client, enableCalendarTasks, normalizedViewMode, showTasksOnCalendar, taskStore]);
 
   useEffect(() => {
     if (client && calendars.length > 0 && dateRange) {
@@ -704,7 +704,7 @@ export default function CalendarPage() {
     };
     window.addEventListener("keydown", handleKey);
     return () => window.removeEventListener("keydown", handleKey);
-  }, [navigatePrev, navigateNext, goToToday, setViewMode, openCreateModal, showEventModal, detailEvent]);
+  }, [navigatePrev, navigateNext, goToToday, setViewMode, openCreateModal, showEventModal, detailEvent, enableCalendarTasks]);
 
   const visibleEvents = useMemo(() =>
     events.filter((e) => {