fix(web): isolate subscriber callbacks in pty.onData with try-catch

A throwing callback (e.g. ws.send on a closed socket) would abort the
for-of loop, causing remaining subscribers to miss the data chunk and
skipping the ring buffer update — corrupting replay history for future
reconnections. Wrapping each call in try-catch keeps all subscribers
independent and ensures the buffer update always runs.

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

packages/web/server/mux-websocket.ts

@@ -273,9 +273,14 @@ class TerminalManager {
 
     // Wire up data events
     pty.onData((data: string) => {
-      // Push to all subscribers
+      // Push to all subscribers — isolate each callback so a throw in one
+      // (e.g. a closed ws.send) doesn't abort the loop or skip the buffer.
       for (const callback of terminal.subscribers) {
-        callback(data);
+        try {
+          callback(data);
+        } catch (err) {
+          console.error("[MuxServer] Subscriber callback threw:", err);
+        }
       }
 
       // Append to ring buffer