feat: dynamic database storage size with PVC expansion

- Add dbStorageSize column to Application entity (default: 1Gi)
- Add dbStorageSize to CreateApplicationDto, frontend types
- Use dynamic storage size in K8s deployDatabase instead of hardcoded 5Gi
- Deploy page: storage size selector with +/- buttons (min 1GB, max 100GB)
- Auto-suggest storage based on DB dump file size (3x dump size, min 1GB)
- Show DB storage in Review step
- App detail: Database Storage section with expand button
- GET /applications/:id/db-storage — read current PVC size from K8s
- PATCH /applications/:id/db-storage — expand PVC (only increase, no shrink)
- PVC resize uses JSON patch on K8s API

frontend/src/types/index.ts

@@ -20,6 +20,7 @@ export interface Application {
   dbVersion?: string;
   dbUsername?: string;
   dbPassword?: string;
+  dbStorageSize?: string;
   gitUrl?: string;
   gitToken?: string;
   gitBranch?: string;
@@ -97,6 +98,7 @@ export interface CreateApplicationDto {
   dbVersion?: string;
   dbUsername?: string;
   dbPassword?: string;
+  dbStorageSize?: string;
   gitUrl?: string;
   gitToken?: string;
   gitBranch?: string;