Bug fixes

• Fix a layout shift that happened right after a message finished rendering.
• Make the `+` / `-` controls in sidebars consistent across sections.
• Bind `Cmd+J` to open the terminal.
• Add a Stop button for long-running threads.
• Enable web query for Gemini.
• Reorganize Settings into clear groups: Cowork, Cloud, and Powers.
• Add a one-click button to send chat history when reporting a rendering or system-level issue.
• Add a commit / push / PR modal.
• Polish the onboarding flow end-to-end.