feat: 添加 MCP 健康检查 API 路由

新增 /api/mcp/health/[mcpType] 动态路由，用于检查各 MCP 服务器的健康状态。

- 支持 novel-translator、novel-platform-user、novel-platform-admin、template-241-mcp-app
- 返回健康状态、延迟、URL 和认证类型
- 405 Method Not Allowed 视为健康（MCP 使用 POST）

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend-v2/app/api/mcp/health/[mcpType]/route.ts

@@ -0,0 +1,66 @@
+import { NextRequest } from 'next/server';
+
+// MCP 服务器配置
+const MCP_SERVERS: Record<string, { url: string; authType: string }> = {
+  'novel-translator': {
+    url: 'https://d8d-ai-vscode-8080-223-236-template-6-group.dev.d8d.fun/mcp',
+    authType: 'none',
+  },
+  'novel-platform-user': {
+    url: 'https://d8d-ai-vscode-8080-223-238-template-6-group.dev.d8d.fun/mcp/',
+    authType: 'jwt',
+  },
+  'novel-platform-admin': {
+    url: 'https://d8d-ai-vscode-8080-223-238-template-6-group.dev.d8d.fun/admin-mcp/',
+    authType: 'jwt',
+  },
+  'template-241-mcp-app': {
+    url: 'https://d8d-ai-vscode-8080-223-241-template-6-group.dev.d8d.fun/mcp',
+    authType: 'none',
+  },
+};
+
+export async function GET(
+  request: NextRequest,
+  { params }: { params: { mcpType: string } }
+) {
+  const { mcpType } = params;
+  const config = MCP_SERVERS[mcpType];
+
+  if (!config) {
+    return new Response(
+      JSON.stringify({ healthy: false, error: '未知的 MCP 类型' }),
+      { status: 404, headers: { 'Content-Type': 'application/json' } }
+    );
+  }
+
+  try {
+    const startTime = Date.now();
+    const response = await fetch(config.url, {
+      method: 'GET',
+      headers: { 'Accept': 'application/json' },
+    });
+    const latency = Date.now() - startTime;
+
+    const healthy = response.ok || response.status === 405; // 405 Method Not Allowed 也算健康（MCP 用 POST）
+
+    return new Response(
+      JSON.stringify({
+        healthy,
+        status: response.ok ? 'healthy' : 'unhealthy',
+        latency,
+        url: config.url,
+        authType: config.authType,
+      }),
+      { status: 200, headers: { 'Content-Type': 'application/json' } }
+    );
+  } catch (error) {
+    return new Response(
+      JSON.stringify({
+        healthy: false,
+        error: error instanceof Error ? error.message : String(error),
+      }),
+      { status: 200, headers: { 'Content-Type': 'application/json' } }
+    );
+  }
+}