feat: Complete light mode implementation with semantic theme system

- Add comprehensive light/dark mode CSS variables with semantic naming
- Implement theme-aware scrollbars using CSS variables
- Add light mode backgrounds: --bg-base, --bg-elevated, --bg-surface, etc.
- Add theme-aware borders: --border-base, --border-panel, --border-subtle
- Add semantic text colors: --foreground-secondary, --foreground-subtle
- Convert oklch colors to hex for better compatibility
- Add theme awareness to CodeMirror editors
- Update dark mode colors for consistency (background, sidebar, card, muted, input)
- Add Tailwind color mappings for semantic classes

package.json

@@ -58,6 +58,7 @@
     "@types/qrcode": "^1.5.5",
     "@types/speakeasy": "^2.0.10",
     "@uiw/codemirror-extensions-langs": "^4.24.1",
+    "@uiw/codemirror-theme-github": "^4.25.4",
     "@uiw/react-codemirror": "^4.24.1",
     "@xterm/addon-clipboard": "^0.1.0",
     "@xterm/addon-fit": "^0.10.0",