fix: restore three and @react-three/fiber required by @shadergradient/react

@shadergradient/react imports these at runtime even though they are not
declared as peer dependencies in its package.json.

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

package.json

@@ -54,6 +54,7 @@
   "dependencies": {
     "@next/bundle-analyzer": "^15.1.7",
     "@prisma/client": "^5.22.0",
+    "@react-three/fiber": "^9.5.0",
     "@sentry/nextjs": "^10.36.0",
     "@shadergradient/react": "^2.4.20",
     "@swc/helpers": "^0.5.19",
@@ -82,7 +83,8 @@
     "react-markdown": "^10.1.0",
     "redis": "^5.8.2",
     "sanitize-html": "^2.17.0",
-    "tailwind-merge": "^2.6.0"
+    "tailwind-merge": "^2.6.0",
+    "three": "^0.183.1"
   },
   "devDependencies": {
     "@eslint/eslintrc": "^3",