feat: add ai-powered commit message helpers

[yasunogithub]

This Pull Request fixes/closes #{issue_num}.

It changes the following:

• Add commit helper with a configurable
  RON-based commit helper system supporting multiple helpers
• Add helper selection UI with keyboard navigation, hotkeys, and
  smooth spinner animations for background execution
• Implement template variables ({staged_diff}, {staged_files},
  {branch_name}) for flexible command customization and improved
  error handling
  I followed the checklist:
• I added unittests
• I ran make check without errors
• I tested the overall application
• I added an appropriate item to the changelog