feat(settings): redesign UI with Compact Utility aesthetic

- Add side-by-side provider cards (Claude/Codex) with uniform height
- Implement iOS-style toggle switches replacing checkboxes
- Add progress bars with color thresholds (green/yellow/red)
- Create configuration modal for provider-specific settings
- Add collapsible card behavior (collapsed when tracking disabled)
- Implement 2-column settings grid for general preferences
- Update window size to 700x720 for better layout
- Add CSS design system with variables for colors, spacing, typography
- Improve keyboard accessibility (tabindex, aria-expanded, Enter/Space)

Author: leonardocouy

src-tauri/src/windows.rs

@@ -15,7 +15,7 @@ pub fn open_settings_window<R: Runtime>(app: &AppHandle<R>) -> tauri::Result<()>
         WebviewUrl::App("index.html".into()),
     )
     .title("Claudometer Settings")
-    .inner_size(460.0, 650.0)
+    .inner_size(700.0, 720.0)
     .resizable(false)
     .minimizable(false)
     .maximizable(false)