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]/contacts/page.tsx

@@ -122,7 +122,7 @@ export default function ContactsPage() {
   const individuals = useMemo(() => contacts.filter(c => c.kind !== 'group'), [contacts]);
   const selectedContact = contacts.find((c) => c.id === selectedContactId) || null;
   const selectedGroup = selectedGroupId ? contacts.find(c => c.id === selectedGroupId) || null : null;
-  const selectedGroupMembers = selectedGroupId ? getGroupMembers(selectedGroupId) : [];
+  const selectedGroupMembers = useMemo(() => selectedGroupId ? getGroupMembers(selectedGroupId) : [], [selectedGroupId, getGroupMembers]);
 
   // Collect all unique keywords across contacts
   const allKeywords = useMemo(() => {
@@ -307,7 +307,7 @@ export default function ContactsPage() {
     }
   };
 
-  const handleSelectGroup = (id: string) => {
+  const _handleSelectGroup = (id: string) => {
     setSelectedGroupId(id);
     setActiveCategory({ groupId: id });
     setView("group-detail");