feat(ui): enhance UI with animations, dark mode support and and improved components

- Add framer-motion page transitions and AnimatePresence support
- Add dark mode support across all components
- Create reusable UI components (Button, Badge, Card, EmptyState, Input, Toast, Skeleton)
- Add CSS custom properties for consistent theming
- Add animation variants and utility functions
- Improve ChatArea, Sidebar, TriggersPanel with animations

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

desktop/package.json

@@ -22,9 +22,13 @@
   "dependencies": {
     "@tauri-apps/api": "^2",
     "@tauri-apps/plugin-opener": "^2",
+    "clsx": "^2.1.1",
+    "framer-motion": "^12.36.0",
     "lucide-react": "^0.577.0",
     "react": "^19.1.0",
     "react-dom": "^19.1.0",
+    "smol-toml": "^1.6.0",
+    "tailwind-merge": "^3.5.0",
     "tweetnacl": "^1.0.3",
     "zustand": "^5.0.11"
   },