feat(storage): implement user-group level file management dashboard and APIs

- Expose user-scoped CRUD APIs under `/api/v1/upload` (my files query, stats, rename, delete)
- Update backend handlers and routers with ownership validation checks
- Create a dedicated frontend personal file manager card-list and upload button under `/files`
- Add comprehensive backend test coverage and update API docs

frontend/app/(main)/files/page.tsx

@@ -0,0 +1,5 @@
+import {UserFilesMain} from "@/components/common/user/files"
+
+export default function UserFilesPage() {
+  return <UserFilesMain />
+}