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/files/file-upload-area.tsx

@@ -2,7 +2,7 @@
 
 import { useCallback, useState } from "react";
 import { useTranslations } from "next-intl";
-import { Upload, FolderPlus, FilePlus, FolderUp } from "lucide-react";
+import { Upload, FolderPlus, FilePlus } from "lucide-react";
 import { Button } from "@/components/ui/button";
 import { getDroppedFilesAndFolders } from "@/lib/webdav/drop-utils";