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)

components/contacts/__tests__/contact-list.test.tsx

@@ -1,4 +1,4 @@
-import { render, screen, fireEvent } from '@testing-library/react';
+import { render, screen } from '@testing-library/react';
 import { describe, it, expect, vi } from 'vitest';
 import { ContactList } from '../contact-list';
 import type { ContactCard } from '@/lib/jmap/types';
@@ -22,7 +22,7 @@ const bob = makeContact({
   emails: { e0: { address: 'bob@example.com' } },
 });
 
-const group = makeContact({
+const _group = makeContact({
   id: '3',
   kind: 'group',
   name: { components: [{ kind: 'given', value: 'Team' }], isOrdered: true },