feat(center): enhance health check with DB readiness

Fabric.Backend.Center/src/common/health.controller.ts

@@ -1,9 +1,25 @@
-import { Controller, Get } from '@nestjs/common';
+import { Controller, Get, ServiceUnavailableException } from '@nestjs/common';
+import { DataSource } from 'typeorm';
 
 @Controller('healthz')
 export class HealthController {
+  constructor(private readonly dataSource: DataSource) {}
+
   @Get()
-  get() {
-    return { ok: true, service: 'center' };
+  async get() {
+    try {
+      await this.dataSource.query('SELECT 1');
+      return {
+        ok: true,
+        service: 'center',
+        database: 'ready',
+      };
+    } catch {
+      throw new ServiceUnavailableException({
+        ok: false,
+        service: 'center',
+        database: 'not_ready',
+      });
+    }
   }
 }

docs/TODO-backend-center-guild.md

@@ -31,7 +31,7 @@
 
 ### 1.3 Center 运维能力
 - [x] 审计日志（auth/node 关键操作）
-- [ ] 健康检查深化（DB ready）
+- [x] 健康检查深化（DB ready）
 - [x] 配置校验（启动时必填项检查）
 
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