refactor(mcp): hoist McpServer to singleton, read name/version from package.json

- server instantiated once in constructor, tools registered once
- per-request transport created fresh and closed in finally to reset server state
- name and version sourced from package.json instead of hard-coded strings

src/mcp/mcp.service.ts

@@ -11,8 +11,12 @@ import { BrowserService } from '../browser/browser.service';
 import { CodeExecutorService } from '../code-executor/code-executor.service';
 import { ScenarioService } from '../scenario/scenario.service';
 
+import pkg from '../../package.json';
+
 @Injectable()
 export class McpService {
+  private readonly server: McpServer;
+
   constructor(
     private readonly authService: AuthService,
     private readonly sessionService: SessionService,
@@ -20,9 +24,13 @@ export class McpService {
     private readonly browserService: BrowserService,
     private readonly codeExecutor: CodeExecutorService,
     private readonly scenarioService: ScenarioService,
-  ) {}
+  ) {
+    this.server = new McpServer({ name: pkg.name, version: pkg.version });
+    this.registerTools();
+  }
 
-  private registerTools(server: McpServer): void {
+  private registerTools(): void {
+    const server = this.server;
 
     // ── Auth ──────────────────────────────────────────────────────────────────
 
@@ -446,14 +454,12 @@ export class McpService {
   }
 
   async handle(req: Request, res: Response): Promise<void> {
-    const server = new McpServer({ name: 'liquio-qa-bot', version: '1.0.0' });
-    this.registerTools(server);
-
-    const transport = new StreamableHTTPServerTransport({
-      sessionIdGenerator: undefined, // stateless — no session management
-    });
-
-    await server.connect(transport);
-    await transport.handleRequest(req, res, req.body);
+    const transport = new StreamableHTTPServerTransport({ sessionIdGenerator: undefined });
+    await this.server.connect(transport);
+    try {
+      await transport.handleRequest(req, res, req.body);
+    } finally {
+      await transport.close();
+    }
   }
 }