1.2.8

Add Gemini Plan (OAuth) support (#513)

* feat: Add Gemini plan provider with OAuth support

- Introduced Gemini plan as a new provider type with OAuth integration.
- Implemented authentication flow including token exchange and callback server.
- Updated settings schema to include Gemini provider and associated OAuth fields.
- Enhanced chat model settings to support Gemini-specific configurations.
- Added migration logic to transition existing settings to support the new provider.
- Comprehensive tests added for migration and Gemini functionality.

* chore: Update Gemini plan modal and connection descriptions

* docs: Update README and settings to warn about risks of third-party OAuth access for Claude subscriptions

- Added a warning in the README about the risks associated with connecting a Claude subscription, including potential account bans.
- Introduced a warning message in the PlanConnectionsSection to inform users about the restrictions on third-party OAuth access and advised caution in usage.
- Enhanced styles for warning messages to improve visibility and user awareness.

* fix: Fix lint

* fix: Resolve coderabbitai review