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

backend/src/kubernetes/kubernetes.service.ts

@@ -26,6 +26,7 @@ interface ManifestContext {
   dbUsername: string;
   dbPassword: string;
   dbVersion: string;
+  dbStorageSize: string;
 }
 
 @Injectable()
@@ -99,6 +100,7 @@ export class KubernetesService implements OnModuleInit {
       dbUsername: app.dbUsername || 'appuser',
       dbPassword: app.dbPassword || this.generatePassword(),
       dbVersion: app.dbVersion || '',
+      dbStorageSize: app.dbStorageSize || '1Gi',
     };
 
     const manifests: Record<string, any> = {};
@@ -396,7 +398,7 @@ export class KubernetesService implements OnModuleInit {
     await this.createDbSecret(coreApi, ctx.namespace, ctx.appName, ctx.dbPassword, ctx.dbUsername);
 
     // Create PVC for DB
-    await this.createPVC(coreApi, ctx.namespace, dbName, '5Gi');
+    await this.createPVC(coreApi, ctx.namespace, dbName, ctx.dbStorageSize);
 
     // Deploy database
     const isPostgres = ctx.databaseType === DatabaseType.POSTGRESQL;
@@ -1025,6 +1027,72 @@ export class KubernetesService implements OnModuleInit {
     return { success: true, logs };
   }
 
+  /**
+   * Resize (expand) the database PVC for an application.
+   * K8s only supports PVC expansion, not shrinking.
+   */
+  async resizeDatabasePvc(app: Application, newSize: string): Promise<{ success: boolean; message: string }> {
+    const { coreApi } = await this.getK8sClient(app.clusterId);
+    const namespace = `user-${app.userId.split('-')[0]}`;
+    const pvcName = `${app.name}-db`;
+
+    try {
+      // Read current PVC to check current size
+      const currentPvc = await coreApi.readNamespacedPersistentVolumeClaim(pvcName, namespace);
+      const currentSize = currentPvc.body.spec?.resources?.requests?.storage || '1Gi';
+
+      const currentGi = parseInt(currentSize.replace('Gi', ''), 10) || 1;
+      const newGi = parseInt(newSize.replace('Gi', ''), 10) || 1;
+
+      if (newGi <= currentGi) {
+        return { success: false, message: `New size (${newSize}) must be larger than current size (${currentSize})` };
+      }
+
+      // Patch PVC to expand
+      const patch = [
+        {
+          op: 'replace',
+          path: '/spec/resources/requests/storage',
+          value: newSize,
+        },
+      ];
+
+      await coreApi.patchNamespacedPersistentVolumeClaim(
+        pvcName,
+        namespace,
+        patch,
+        undefined,
+        undefined,
+        undefined,
+        undefined,
+        undefined,
+        { headers: { 'Content-Type': 'application/json-patch+json' } },
+      );
+
+      this.logger.log(`Resized PVC ${pvcName} from ${currentSize} to ${newSize}`);
+      return { success: true, message: `Database storage expanded from ${currentSize} to ${newSize}` };
+    } catch (e: any) {
+      this.logger.error(`Failed to resize PVC ${pvcName}: ${e.message}`);
+      return { success: false, message: e.body?.message || e.message || 'Failed to resize database storage' };
+    }
+  }
+
+  /**
+   * Get current PVC size for an application's database.
+   */
+  async getDatabasePvcSize(app: Application): Promise<string> {
+    try {
+      const { coreApi } = await this.getK8sClient(app.clusterId);
+      const namespace = `user-${app.userId.split('-')[0]}`;
+      const pvcName = `${app.name}-db`;
+
+      const pvc = await coreApi.readNamespacedPersistentVolumeClaim(pvcName, namespace);
+      return pvc.body.spec?.resources?.requests?.storage || app.dbStorageSize || '1Gi';
+    } catch {
+      return app.dbStorageSize || '1Gi';
+    }
+  }
+
   private generatePassword(length = 24): string {
     const chars = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789!@#$%';
     let password = '';