feat: migrate backend foundation to NestJS

apps/api/src/nest/api.interceptor.ts

@@ -0,0 +1,14 @@
+import type { CallHandler, ExecutionContext, NestInterceptor } from '@nestjs/common';
+import { Injectable } from '@nestjs/common';
+import type { FastifyReply } from 'fastify';
+import type { Observable } from 'rxjs';
+import { map } from 'rxjs/operators';
+import { withResponseMeta } from '../core/http.js';
+
+@Injectable()
+export class ApiEnvelopeInterceptor implements NestInterceptor {
+  intercept(context: ExecutionContext, next: CallHandler): Observable<unknown> {
+    const reply = context.switchToHttp().getResponse<FastifyReply>();
+    return next.handle().pipe(map(body => withResponseMeta(body, String(reply.getHeader('x-request-id') || ''))));
+  }
+}