fix: remove worker mutex and increase collab timeout to 120s

- Remove workerBusy promise chain (mutex) in src/index.ts: each
  StreamableHTTPServerTransport is stateless and per-request, so
  concurrent handling within a worker is safe. Eliminates request
  starvation when long page writes are in flight.
- Raise the Hocuspocus safety timeout in collaboration.ts from 25 s
  to 120 s, giving large documents enough time to complete the Yjs
  sync phase before the hard abort fires.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

src/index.ts

@@ -873,8 +873,8 @@ if (cluster.isPrimary) {
   });
 } else {
   // ── Worker: cada uno tiene su propio McpServer singleton ──
-  // El mutex serializa las requests dentro de este worker (stateless, 1 request a la vez por worker)
-  let workerBusy: Promise<void> = Promise.resolve();
+  // Sin mutex: cada request se atiende concurrentemente dentro del worker.
+  // StreamableHTTPServerTransport es stateless (uno por request), sin estado compartido.
 
   async function handleMcpRequest(req: IncomingMessage, res: ServerResponse): Promise<void> {
     const transport = new StreamableHTTPServerTransport({
@@ -893,16 +893,14 @@ if (cluster.isPrimary) {
       res.writeHead(404).end("Not found");
       return;
     }
-    workerBusy = workerBusy
-      .then(() => handleMcpRequest(req, res))
-      .catch((err) => {
-        console.error(`[docmost-mcp] Worker PID=${process.pid} error:`, err);
-        if (!res.headersSent) {
-          res.writeHead(500, { "Content-Type": "application/json" }).end(
-            JSON.stringify({ jsonrpc: "2.0", error: { code: -32603, message: String(err) }, id: null })
-          );
-        }
-      });
+    handleMcpRequest(req, res).catch((err) => {
+      console.error(`[docmost-mcp] Worker PID=${process.pid} error:`, err);
+      if (!res.headersSent) {
+        res.writeHead(500, { "Content-Type": "application/json" }).end(
+          JSON.stringify({ jsonrpc: "2.0", error: { code: -32603, message: String(err) }, id: null })
+        );
+      }
+    });
   });
 
   httpServer.listen(8080, () => {

src/lib/collaboration.ts

@@ -67,7 +67,7 @@ export async function updatePageContentRealtime(
     const timer = setTimeout(() => {
       if (provider) provider.destroy();
       reject(new Error("Connection timeout to collaboration server"));
-    }, 25000);
+    }, 120000);
 
     const provider = new HocuspocusProvider({
       url: wsUrl,