validate environment variables at build time

package.json

@@ -27,6 +27,7 @@
     "@next/mdx": "15.3.0-canary.45",
     "@octokit/graphql": "^8.2.1",
     "@octokit/graphql-schema": "^15.26.0",
+    "@t3-oss/env-nextjs": "^0.12.0",
     "@upstash/redis": "^1.34.7",
     "clsx": "^2.1.1",
     "copy-to-clipboard": "^3.3.3",
@@ -74,7 +75,7 @@
     "@types/node": "^22.14.0",
     "@types/prop-types": "^15.7.14",
     "@types/react": "^19.1.0",
-    "@types/react-dom": "^19.1.1",
+    "@types/react-dom": "^19.1.2",
     "@types/react-is": "^19.0.0",
     "babel-plugin-react-compiler": "19.0.0-beta-e993439-20250405",
     "cross-env": "^7.0.3",