## What changed
- Bundle `ada`, `babbage`, `curie`, `cushman`, `dali`, and `davinci` themes for configuration and the theme picker, preserving precedence and invalid-file warnings for custom themes with the same names.
- Use `codex.accent` for active and selected controls on truecolor and 256-color terminals, retaining existing fallbacks at lower color depths.
- Honor terminal-default diff backgrounds and clear matching gutter fills, allowing `dali` and `davinci` to show diffs without background fills.
- Restrict Windows native palette fallback to `ConsoleWindowClass` so a ConPTY palette is not mistaken for the renderer's colors when OSC probing fails.
## Testing
Add tests and snapshots for theme preview, selection, cancellation, custom-theme precedence, invalid-file warnings, accent color depth, and disabling individual diff fills.
GitOrigin-RevId: 72f3ef08f82626436dd2d80d40210cc77e1a5616
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