Fix UI padding and text flush against container edges

- Remove global * { padding: 0 } reset that was overriding all Tailwind
  padding classes (unlayered CSS beats Tailwind v4 @layer utilities)
- Add color-scheme: dark to fix native form controls (select dropdowns)
  rendering with white backgrounds
- Make sidebar responsive (25% width, min 224px, max 320px)
- Increase internal padding on TopBar, Sidebar, ProjectList, StatusBar
- Add flex-shrink-0 to TopBar status indicators to prevent clipping
- Allow project action buttons to wrap on narrow sidebars
- Increase terminal view padding for breathing room

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/src/index.css

@@ -12,13 +12,9 @@
   --success: #3fb950;
   --warning: #d29922;
   --error: #f85149;
+  color-scheme: dark;
 }
 
-* {
-  margin: 0;
-  padding: 0;
-  box-sizing: border-box;
-}
 
 html, body, #root {
   height: 100%;