Add setting to hide/disable git status bar

Feature Request

Add a setting to hide or disable the git status bar that shows the branch tracking info (e.g., "main ← main") and the "Create PR" button at the bottom of the Claude Code interface.

Why:

• It takes up vertical space that not all users need
• Some users working in shared repos don't need the PR creation UI constantly visible
• There's no way to toggle it off currently

Suggested solution:
A boolean setting like showGitStatusBar: false in settings.json, or a toggle in the UI settings.

Environment:

• Claude Code v2.1.79
• macOS (Claude desktop app)