feat: Add backend support for one-click Rust server deployment

Add deploy endpoint, DTO, NATS command publisher, and WebSocket bridge
subscription to support the one-click server deployment feature via the
companion agent.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend-nest/src/services/nats.service.ts

@@ -70,4 +70,13 @@ export class NatsService implements OnModuleInit, OnModuleDestroy {
       timestamp: new Date().toISOString(),
     });
   }
+
+  /** Publish a deploy command to a specific license's companion agent */
+  async sendDeployCommand(licenseId: string, config: Record<string, unknown>): Promise<void> {
+    await this.publish(`corrosion.${licenseId}.cmd.deploy`, {
+      action: 'deploy',
+      config,
+      timestamp: new Date().toISOString(),
+    });
+  }
 }