feat: 重构配置管理，使用数据库替代环境变量，优化系统配置读取

server/api/health.get.ts

@@ -1,7 +1,7 @@
 // server/api/health.get.ts - 服务健康检查接口
-import { serverEnv } from "~~/server/utils/env";
 import { apiOk } from "~~/server/utils/response";
 import { SERVICE_VERSION } from "~~/server/utils/runtimeState";
+import { getSysConfig } from "~~/server/utils/sysConfig";
 
 /**
  * 健康检查不需要鉴权
@@ -9,11 +9,12 @@ import { SERVICE_VERSION } from "~~/server/utils/runtimeState";
  * 这个接口用于部署平台、Docker healthcheck 或人工确认服务是否启动；
  * 返回模型名，但不返回 API Key、baseURL 或其他敏感配置
  */
-export default defineEventHandler(() => {
+export default defineEventHandler(async () => {
+  const cfg = await getSysConfig();
   return apiOk({
     status: "ok" as const,
     message: "AI题库服务运行正常",
     version: SERVICE_VERSION,
-    model: serverEnv.openAiModel
+    model: cfg.openAiModel
   });
 });

server/api/stats.get.ts

@@ -18,7 +18,7 @@ export default defineEventHandler(async (event) => {
 
   try {
     const [runtimeStats, qa_records_count] = await Promise.all([
-      Promise.resolve(getRuntimeStats()),
+      getRuntimeStats(),
       prisma.qaRecord.count({ where: { userId } })
     ]);