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/settings/email-settings.tsx

@@ -4,7 +4,7 @@ import { useState, useCallback } from 'react';
 import { useTranslations } from 'next-intl';
 import { useConfig } from '@/hooks/use-config';
 import { useSettingsStore } from '@/stores/settings-store';
-import type { ArchiveMode, HoverAction, HoverActionsMode, HoverActionsCorner } from '@/stores/settings-store';
+import type { ArchiveMode, HoverAction } from '@/stores/settings-store';
 import { ALL_HOVER_ACTIONS } from '@/stores/settings-store';
 import { useAuthStore } from '@/stores/auth-store';
 import { useEmailStore } from '@/stores/email-store';