feat: 平台管理 - 模型提供商连接测试功能

- 前端：添加"测试连接"按钮，支持实时测试 provider 可用性
- 后端：新增 TestProvider 接口，发送测试请求验证配置
- 路由：注册 POST /providers/{id}/test 端点
- 初始化：LLM Manager 优先从数据库加载 providers，失败时回退到环境变量
- .gitignore：忽略构建产物 server/bin/、server-* 和 test-* 目录

apps/web/src/app/platform/providers/page.tsx

@@ -26,7 +26,7 @@ import {
   AlertDialogTitle,
 } from "@/components/ui/alert-dialog";
 import { toast } from "sonner";
-import { Plus, Pencil, Power, Trash2, Cpu, CheckCircle2, XCircle } from "lucide-react";
+import { Plus, Pencil, Power, Trash2, Cpu, CheckCircle2, XCircle, Wifi } from "lucide-react";
 import { Pagination } from "@/components/ui/pagination";
 
 interface ProviderForm {
@@ -55,6 +55,7 @@ export default function PlatformProvidersPage() {
   const [editing, setEditing] = useState<ProviderForm | null>(null);
   const [deleteTarget, setDeleteTarget] = useState<ModelProvider | null>(null);
   const [page, setPage] = useState(1);
+  const [testingId, setTestingId] = useState<string | null>(null);
 
   const { data: providers } = useQuery({
     queryKey: ["platformProviders"],
@@ -126,6 +127,31 @@ export default function PlatformProvidersPage() {
     onError: (e: Error) => toast.error(e.message),
   });
 
+  const testConnection = useMutation({
+    mutationFn: (id: string) => api.post(`/api/v1/platform/providers/${id}/test`),
+    onSuccess: (data: any) => {
+      if (data.success) {
+        toast.success("连接测试成功", {
+          description: data.response || "Provider 响应正常",
+        });
+      } else {
+        toast.error("连接测试失败", {
+          description: data.message || "未知错误",
+        });
+      }
+      setTestingId(null);
+    },
+    onError: (e: Error) => {
+      toast.error("连接测试失败", { description: e.message });
+      setTestingId(null);
+    },
+  });
+
+  const handleTest = (id: string) => {
+    setTestingId(id);
+    testConnection.mutate(id);
+  };
+
   const handleSubmit = () => {
     if (!editing) return;
     if (!editing.name || !editing.base_url) {
@@ -222,6 +248,16 @@ export default function PlatformProvidersPage() {
               >
                 <Pencil className="h-3 w-3" /> 编辑
               </Button>
+              <Button
+                size="sm"
+                variant="ghost"
+                className="h-7 gap-1 text-xs"
+                onClick={() => handleTest(p.id)}
+                disabled={testingId === p.id}
+              >
+                <Wifi className="h-3 w-3" />
+                {testingId === p.id ? "测试中..." : "测试连接"}
+              </Button>
               <Button
                 size="sm"
                 variant="ghost"