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/app.module.ts

@@ -2,6 +2,8 @@ import { Module } from '@nestjs/common';
 import { ConfigModule, ConfigService } from '@nestjs/config';
 import { TypeOrmModule } from '@nestjs/typeorm';
 import { BullModule } from '@nestjs/bull';
+import { ThrottlerModule, ThrottlerGuard } from '@nestjs/throttler';
+import { APP_GUARD } from '@nestjs/core';
 import { AuthModule } from './auth/auth.module';
 import { UsersModule } from './users/users.module';
 import { ApplicationsModule } from './applications/applications.module';
@@ -15,6 +17,7 @@ import { SnapshotsModule } from './snapshots/snapshots.module';
 import { LifecycleModule } from './lifecycle/lifecycle.module';
 import { ApplicationMigrationsModule } from './application-migrations/application-migrations.module';
 import { AdminModule } from './admin/admin.module';
+import { HealthModule } from './health/health.module';
 import configuration from './config/configuration';
 
 @Module({
@@ -54,6 +57,14 @@ import configuration from './config/configuration';
       inject: [ConfigService],
     }),
 
+    ThrottlerModule.forRoot([
+      {
+        name: 'default',
+        ttl: 60_000,
+        limit: 120,
+      },
+    ]),
+
     // Feature modules
     AuthModule,
     UsersModule,
@@ -68,6 +79,13 @@ import configuration from './config/configuration';
     LifecycleModule,
     ApplicationMigrationsModule,
     AdminModule,
+    HealthModule,
+  ],
+  providers: [
+    {
+      provide: APP_GUARD,
+      useClass: ThrottlerGuard,
+    },
   ],
 })
 export class AppModule {}