fix(server): prevent send-on-closed-channel panic in session title generation

[Piyush0049]

Description

This PR fixes a critical runtime concurrency bug in SessionManager.RunSession where asynchronous session title generation could attempt to send events on a closed channel, causing the server process to crash.

Root Cause

When a session turn required title generation, sm.generateTitle was spawned asynchronously as a background goroutine writing title events to streamChan. If the conversation stream (RunStream) terminated early due to cancellation, completion, or error, the function returned immediately and triggered defer close(streamChan). When the background title goroutine subsequently attempted to emit runtime.SessionTitle to streamChan, sending on the closed channel caused a runtime panic.

Key Changes

• WaitGroup Lifecycle Coordination: Added a sync.WaitGroup around the asynchronous generateTitle goroutine and placed wg.Wait() before the return paths in RunSession. This guarantees that close(streamChan) cannot execute until title generation completes or safely aborts on context cancellation.
• Graceful Stream Consumer Loop: Replaced a direct return with break inside the RunStream consumer loop when encountering a context error. This ensures execution always falls through to wg.Wait(), guaranteeing background synchronization even during early client disconnects or stream aborts.

Verification

• Ran task lint and golangci-lint run cleanly with zero issues reported.
• Verified that context cancellation in generateTitle unblocks immediately via select on ctx.Done(), preventing hangs or deadlocks.

[aheritier]

Same here @Piyush0049

Please provide more details about the issue you are trying to solve. Is it something which happens often? What are the symptoms?

Right now the PR doesn't provide enough context to understand if you are fixing a bug or if these are just code reviews by an LLM which could easily hallucinate bugs.

Thanks