Moves the "Generating commit message" notification from VS Code's static NLS to the dynamic i18next infrastructure, ensuring it gets properly translated.

- Simplifies the translation key to `git.generatingCommitMessage`.
- Fixes the i18n setup script to resolve the correct locales path.
- Stabilizes the `t()` helper to prevent race conditions with language changes.
- Removes the now-obsolete key from all `package.nls.*.json` files to clean up the codebase.

Adds translations for pluginLanguage and commitLanguage to the settings panel for all supported languages.

This ensures that the language selection options in the settings view are properly localized, improving the user experience for non-English speakers.

Adds a comprehensive suite of unit tests for the `generateCommitMessage` function.

The tests cover the following scenarios:
- Git extension not found
- No Git repository found
- No changes in the repository
- AI provider not configured
- Successful commit message generation for tracked files
- Successful commit message generation for untracked files
- Handling of errors when reading untracked files

This ensures the stability and correctness of the commit message generation feature.

…ages experimental feature

The commit language setting has been refactored and moved from the general language settings section. It is now managed by a new dedicated component, .

This component is conditionally rendered within the  section, specifically when the  experimental feature is active. This change ensures that the commit language option is logically grouped with the AI commit message functionality it directly supports, improving the clarity and organization of settings.

Additionally, minor styling adjustments were applied to the  component for improved layout.