feat: Complete NestJS backend scaffold — 22 modules, 39 entities, WebSocket gateway

Full backend rewrite from Rust/Axum to NestJS/TypeScript.
- 22 feature modules (auth, servers, wipes, maps, plugins, players, console,
  chat, team, notifications, settings, schedules, analytics, alerts, status,
  store, webstore, admin, setup, migration, users, licenses)
- 39 TypeORM entities matching PostgreSQL schema (12 migrations)
- Common infrastructure: JWT/RBAC guards, decorators, exception filter
- NATS service with pub/sub/request-reply
- Socket.IO WebSocket gateway with NATS bridge
- Docker: NestJS Dockerfile + updated docker-compose.yml
- Zero compile errors (npx tsc --noEmit clean)

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

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

@@ -0,0 +1,73 @@
+import { Injectable, OnModuleInit, OnModuleDestroy, Logger } from '@nestjs/common';
+import { ConfigService } from '@nestjs/config';
+import { connect, NatsConnection, StringCodec, Subscription } from 'nats';
+
+@Injectable()
+export class NatsService implements OnModuleInit, OnModuleDestroy {
+  private readonly logger = new Logger(NatsService.name);
+  private nc: NatsConnection | null = null;
+  private sc = StringCodec();
+
+  constructor(private config: ConfigService) {}
+
+  async onModuleInit() {
+    try {
+      const url = this.config.get<string>('nats.url') || 'nats://localhost:4222';
+      this.nc = await connect({ servers: url });
+      this.logger.log(`Connected to NATS at ${url}`);
+    } catch (err) {
+      this.logger.warn(`NATS connection failed — running in offline mode: ${(err as Error).message}`);
+    }
+  }
+
+  async onModuleDestroy() {
+    if (this.nc) {
+      await this.nc.drain();
+    }
+  }
+
+  async publish(subject: string, data: Record<string, unknown>): Promise<void> {
+    if (!this.nc) {
+      this.logger.debug(`[OFFLINE] Would publish to ${subject}: ${JSON.stringify(data)}`);
+      return;
+    }
+    this.nc.publish(subject, this.sc.encode(JSON.stringify(data)));
+  }
+
+  async request(subject: string, data: Record<string, unknown>, timeout = 5000): Promise<unknown> {
+    if (!this.nc) {
+      this.logger.debug(`[OFFLINE] Would request ${subject}: ${JSON.stringify(data)}`);
+      return null;
+    }
+    const msg = await this.nc.request(subject, this.sc.encode(JSON.stringify(data)), { timeout });
+    return JSON.parse(this.sc.decode(msg.data));
+  }
+
+  subscribe(subject: string, callback: (data: unknown, subject: string) => void): Subscription | null {
+    if (!this.nc) {
+      this.logger.debug(`[OFFLINE] Would subscribe to ${subject}`);
+      return null;
+    }
+    const sub = this.nc.subscribe(subject);
+    (async () => {
+      for await (const msg of sub) {
+        try {
+          const parsed = JSON.parse(this.sc.decode(msg.data));
+          callback(parsed, msg.subject);
+        } catch {
+          callback(this.sc.decode(msg.data), msg.subject);
+        }
+      }
+    })();
+    return sub;
+  }
+
+  /** Publish a command to a specific license's server */
+  async sendServerCommand(licenseId: string, action: string, payload: Record<string, unknown> = {}): Promise<void> {
+    await this.publish(`corrosion.${licenseId}.cmd.server`, {
+      action,
+      ...payload,
+      timestamp: new Date().toISOString(),
+    });
+  }
+}