Add shadcn/ui components and refactor assistant form to use them.

Set up the design system with Radix-based primitives, theme tokens, and replace custom form controls on the assistant page with shared UI components.

Co-authored-by: Cursor <cursoragent@cursor.com>

package.json

@@ -9,12 +9,16 @@
     "lint": "eslint"
   },
   "dependencies": {
+    "class-variance-authority": "^0.7.1",
     "clsx": "^2.1.1",
     "lucide-react": "^1.17.0",
     "next": "16.2.7",
+    "radix-ui": "^1.4.3",
     "react": "19.2.4",
     "react-dom": "19.2.4",
-    "tailwind-merge": "^3.6.0"
+    "shadcn": "^4.10.0",
+    "tailwind-merge": "^3.6.0",
+    "tw-animate-css": "^1.4.0"
   },
   "devDependencies": {
     "@tailwindcss/postcss": "^4",