🐛 Fix inconsistent error reporting between commit and generate functions

[segersniels]

Description

Improves error handling and consistency across the application by refactoring model types and error reporting.

Added

• New Model type to enforce type safety for model selection
• Better error messaging for git commit failures

Changed

• Refactored model constants to use the new Model type
• Updated Claude model version to use latest tag
• Improved error handling in the message generation process
• Consolidated variables under a single var block
• Simplified the commit flow by reusing the Generate() function

Fixed

• Inconsistent error handling in git commit process by including command output in error messages
• Generation errors now properly reported instead of being silently ignored
• Proper model version handling for Claude 3.5 Sonnet

Removed

• Duplicate code in Commit() function by leveraging existing Generate() function