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/email/email-list-item.tsx

@@ -6,7 +6,7 @@ import { formatDate } from "@/lib/utils";
 import { Email } from "@/lib/jmap/types";
 import { cn } from "@/lib/utils";
 import { Avatar } from "@/components/ui/avatar";
-import { Paperclip, Star, Circle, CheckSquare, Square, Tag, Reply, Forward } from "lucide-react";
+import { Paperclip, Star, Circle, CheckSquare, Square, Reply, Forward } from "lucide-react";
 import { useEmailStore } from "@/stores/email-store";
 import { useSettingsStore, KEYWORD_PALETTE } from "@/stores/settings-store";
 import { useAuthStore } from "@/stores/auth-store";