feat: image upload & preview untuk bug reports via MinIO

- Upload hingga 3 gambar per bug report (FileInput multi-select)
- Backend: POST /api/upload/image → MinIO, GET /api/bugs/images → presigned URL redirect
- Auto-create bucket jika belum ada saat server start
- Preview gambar fullscreen saat thumbnail diklik
- Diterapkan di /bug-reports dan /apps/$appId/errors
- Migrasi storage dari Seafile ke MinIO (minio SDK v8)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/frontend/config/api.ts

@@ -37,6 +37,7 @@ export const API_URLS = {
   getBugs: (page: number, search: string, app: string, status: string) => 
     `/api/bugs?page=${page}&search=${encodeURIComponent(search)}&app=${app}&status=${status}`,
   createBug: () => `/api/bugs`,
+  uploadImage: () => `/api/upload/image`,
   updateBugStatus: (id: string) => `/api/bugs/${id}/status`,
   updateBugFeedback: (id: string) => `/api/bugs/${id}/feedback`,
   createLog: () => `/api/logs`,