v0.27.1: New model support, persistent session settings, and auto-update improvements

New features

- Improved rewind functionality - new /rewind command, plus speed and UX improvements.
- /install-github-app command - New command to install the Factory GitHub app directly from the CLI.
- Images in MCP tool responses - MCP tools can now return images that are properly sent to the LLM.

Bug fixes

- Upgraded to bun 1.3.3
- Safer mechanism to check if ripgrep is installed
- Fixed gpt-5.1-codex reasoning
- Shift+Backspace deletes single characters like Backspace
- Fix GLM4.6 as a spec mode model
- Fix exitSpecMode prompt
- Fix custom models for subdroids
- Prevent console logs during startup
- Fix spec mode for Gemini