Migrate to the cn package

- Ran `npx shadcn@latest migrate cn`: swaps clsx + tailwind-merge for cn
- Import cn from "cn" everywhere (matches what `shadcn add` now writes)
  and remove the src/lib/utils.js re-export shim

Co-Authored-By: Claude Opus 5.5 <[email protected]>

package.json

@@ -10,14 +10,13 @@
   },
   "dependencies": {
     "class-variance-authority": "^0.7.1",
-    "clsx": "^2.1.1",
+    "cn": "^0.4.0",
     "lucide-react": "^1.49.0",
     "next": "^16.3.7",
     "radix-ui": "^1.6.7",
     "react": "^19.3.0",
     "react-dom": "^19.3.0",
     "sharp": "^0.35.5",
-    "tailwind-merge": "^3.7.0",
     "tw-animate-css": "^1.4.0"
   },
   "devDependencies": {