Harden platform security, reliability, and CI after full audit.

Close deployment IDOR and gate stub payment endpoints, add production
secret validation, health probes, Redis-backed build progress, GitHub
Actions CI, expanded tests, billing/k8s refactors, and ops runbooks.

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

backend/src/build/build.module.ts

@@ -1,5 +1,6 @@
 import { Module, forwardRef } from '@nestjs/common';
 import { BuildService } from './build.service';
+import { BuildProgressStore } from './build-progress.store';
 import { KubernetesModule } from '../kubernetes/kubernetes.module';
 import { ClustersModule } from '../clusters/clusters.module';
 
@@ -8,7 +9,7 @@ import { ClustersModule } from '../clusters/clusters.module';
     forwardRef(() => KubernetesModule),
     ClustersModule,
   ],
-  providers: [BuildService],
+  providers: [BuildService, BuildProgressStore],
   exports: [BuildService],
 })
 export class BuildModule {}