Sort chat recents by last activity

[NilayYadav]

Adds an updatedAt field to chat threads that gets bumped whenever a message is written. The Recents sidebar now sorts by last activity instead of creation time, so continuing an old chat bubbles it to the top.

• Backend: new updated_at column with migration backfill from existing messages
• Frontend: sorts sidebar items by updatedAt ?? createdAt; compare pairs take the newest activity across both panes
• Empty state in the sidebar only renders after the first fetch resolves, preventing a flash on load

[chatgpt-codex-connector]

Codex usage limits have been reached for code reviews. Please check with the admins of this repo to increase the limits by adding credits.
Repo admins can enable using credits for code reviews in their settings.

[gemini-code-assist]

Code Review

This pull request introduces an updatedAt field to chat threads to track and sort by the last activity time (e.g., when messages are added or synced). It includes backend database schema updates, a migration to backfill existing threads, API model adjustments, and frontend updates to sort threads by updatedAt and display a "No chats yet" message when the sidebar is empty. There are no review comments, so I have no feedback to provide.

Important

The consumer version of Gemini Code Assist on GitHub is being sunset. Starting June 18, 2026, new organization installations will be blocked, and all code review activity will officially cease on July 17, 2026.
For more details on the timeline and next steps, please review the Help Documentation.