feat(api): cn-app skeleton, toolchain, env loading convention

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

services/api/src/request-id.middleware.ts

@@ -0,0 +1,37 @@
+// services/api/src/request-id.middleware.ts
+// 请求 ID 约定：优先透传上游 x-request-id（网关/前端可携带），否则生成 UUID v4；
+// 挂到 req.id（pino-http 日志字段）并写回响应头 x-request-id，便于全链路排障。
+// genReqId 与本中间件共用 resolveRequestId，先后顺序不影响结果。
+import { randomUUID } from 'node:crypto';
+import type { IncomingMessage, ServerResponse } from 'node:http';
+import type { NestMiddleware } from '@nestjs/common';
+
+interface RequestWithId {
+  id?: string;
+}
+
+export function resolveRequestId(
+  req: IncomingMessage,
+  res: ServerResponse,
+): string {
+  const existing = (req as IncomingMessage & RequestWithId).id;
+  if (existing) {
+    return existing;
+  }
+  const header = req.headers['x-request-id'];
+  const fromHeader = Array.isArray(header) ? header[0] : header;
+  const id =
+    typeof fromHeader === 'string' && fromHeader.trim() !== ''
+      ? fromHeader
+      : randomUUID();
+  (req as IncomingMessage & RequestWithId).id = id;
+  res.setHeader('x-request-id', id);
+  return id;
+}
+
+export class RequestIdMiddleware implements NestMiddleware {
+  use(req: IncomingMessage, res: ServerResponse, next: () => void): void {
+    resolveRequestId(req, res);
+    next();
+  }
+}