feat(api): 搭建 API 与 Worker 骨架及契约基线

NestJS 11 + Fastify 统一错误体与 trace_id，/health 真实探活 DB/Redis，OpenAPI 3.1 契约含 20 个错误码；shared 包提供错误码、权限点、ULID、分页与通用 schema；worker 完成队列进程骨架。

apps/api/src/modules/platform/health/health.controller.ts

@@ -0,0 +1,25 @@
+import { Controller, Get, Inject } from '@nestjs/common';
+import { ApiOkResponse, ApiOperation, ApiResponse, ApiTags } from '@nestjs/swagger';
+
+import { HealthService } from './health.service';
+import { type HealthReport, HealthResponseDto } from './health.types';
+
+@ApiTags('platform')
+@Controller('health')
+export class HealthController {
+  constructor(@Inject(HealthService) private readonly healthService: HealthService) {}
+
+  @Get()
+  @ApiOperation({
+    summary: '健康检查',
+    description: '真实检查 PostgreSQL 与 Redis；任一不可用返回 503 与统一错误体。',
+  })
+  @ApiOkResponse({ type: HealthResponseDto, description: '全部依赖健康' })
+  @ApiResponse({
+    status: 503,
+    description: '依赖不可用（错误码 50002），details 内附各依赖检查结果',
+  })
+  async check(): Promise<HealthReport> {
+    return this.healthService.check();
+  }
+}