feat: add custom domain support with SSL, DNS verification, and billing

Users can assign a custom domain to their app with automatic SSL via
cert-manager. Includes DNS verification flow (CNAME check), Persian
instructions, admin-configurable pricing via PlatformSetting, and
integration into the deploy wizard cost calculation.

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/src/applications/applications.service.ts

@@ -8,7 +8,7 @@ import * as crypto from 'crypto';
 import { Application } from './entities/application.entity';
 import { CreateApplicationDto, UpdateApplicationDto } from './dto/application.dto';
 import { ClustersService } from '../clusters/clusters.service';
-import { UserRole, DatabaseType } from '../common/enums';
+import { UserRole, DatabaseType, CustomDomainStatus } from '../common/enums';
 
 @Injectable()
 export class ApplicationsService {
@@ -76,6 +76,8 @@ export class ApplicationsService {
       this.logger.log(`Generated DB credentials for app "${dto.name}" — user: ${dbUsername}`);
     }
 
+    const customDomain = dto.customDomain?.toLowerCase().trim() || undefined;
+
     const app = this.appsRepository.create({
       ...dto,
       userId,
@@ -84,6 +86,8 @@ export class ApplicationsService {
       dbUsername,
       dbPassword,
       subdomain: `${dto.name}-${userId.split('-')[0]}`,
+      customDomain: customDomain || undefined,
+      customDomainStatus: customDomain ? CustomDomainStatus.PENDING_DNS : CustomDomainStatus.NONE,
     });
     return this.appsRepository.save(app);
   }