We are currently using a "Commits Only" checkbox to switch between Total Contributions and Total Commits. To provide deeper insights, we want to expand this to a "Data Mode" concept with 4 mutually exclusive views:

1. Total (Default): Shows Total Contributions.
2. Public: Shows Public Contributions (Calculated: Total - Private).
3. Private: Shows Private Contributions.
4. Commits: Shows Total Commits.

Tasks:

1. Model (Contributor.mjs): Add totalPublicContributions calculated field.
2. View (ControlsContainer.mjs): Replace "Commits Only" checkbox with a Radio Group for the 4 modes.
3. Grid (GridContainer.mjs):
   • Replace commitsOnly config with dataMode (String enum).
   • Update afterSetDataMode to switch columns (totalContributions, totalPublicContributions, totalPrivateContributions, totalCommits) and update the active sorter.
   • Update activity sparkline logic to use the correct data source (Public = y - py, Private = py).
4. Toolbar (StatusToolbar.mjs): Update summary labels based on the selected mode.