🤖 fix: remove duplicate caught-up event in onChat subscription (#949)

## Summary

The `onChat` handler was pushing a `caught-up` event after
`replayHistory`, but `replayHistory` already sends `caught-up` at the
end of `emitHistoricalEvents`. This resulted in two `caught-up` events
being sent to the client.

## Changes

- Removed the duplicate `push({ type: "caught-up" })` from the router
since `session.replayHistory()` already sends it

## Testing

- Existing integration tests pass (`resumeStream.test.ts`)
- `WorkspaceStore.test.ts` passes
- Typecheck passes

---
_Generated with `mux`_

Author: ammar-agent

src/node/orpc/router.ts

@@ -370,16 +370,11 @@ export const router = (authToken?: string) => {
             push(message);
           });
 
-          // 2. Replay history
+          // 2. Replay history (sends caught-up at the end)
           await session.replayHistory(({ message }) => {
             push(message);
           });
 
-          // 3. Signal that subscription is established and history replay is complete
-          // This allows clients to know when they can safely send messages without
-          // missing events due to async generator setup timing
-          push({ type: "caught-up" });
-
           try {
             yield* iterate();
           } finally {