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/layout/sidebar.tsx

@@ -429,7 +429,7 @@ export function Sidebar({
   className,
 }: SidebarProps) {
   const { sidebarCollapsed: isCollapsed, toggleSidebarCollapsed } = useUIStore();
-  const { primaryIdentity } = useAuthStore();
+  const { primaryIdentity: _primaryIdentity } = useAuthStore();
   const [expandedFolders, setExpandedFolders] = useState<Set<string>>(new Set());
   const [tagsExpanded, setTagsExpanded] = useState(() => {
     try {