Phase 0: scaffold Next.js, Tailwind tokens, Supabase clients, env validation

Next.js 16 App Router with strict TypeScript, Tailwind 4 theme tokens from
docs/UI.md, Vitest, and the three Supabase clients. Env vars are validated
with zod in next.config.ts so dev and build fail fast with a readable error.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

package.json

@@ -0,0 +1,34 @@
+{
+  "name": "game-night-live",
+  "version": "0.1.0",
+  "private": true,
+  "scripts": {
+    "dev": "next dev",
+    "build": "next build",
+    "start": "next start",
+    "lint": "eslint",
+    "test": "vitest run",
+    "test:watch": "vitest"
+  },
+  "dependencies": {
+    "@supabase/ssr": "^0.12.7",
+    "@supabase/supabase-js": "^2.117.2",
+    "next": "16.3.8",
+    "react": "19.2.8",
+    "react-dom": "19.2.8",
+    "server-only": "^0.0.1",
+    "zod": "^4.6.5"
+  },
+  "devDependencies": {
+    "@tailwindcss/postcss": "^4",
+    "@types/node": "^22",
+    "@types/react": "^19",
+    "@types/react-dom": "^19",
+    "@vitest/coverage-v8": "^5.0.3",
+    "eslint": "^9",
+    "eslint-config-next": "16.3.8",
+    "tailwindcss": "^4",
+    "typescript": "^5",
+    "vitest": "^5.0.3"
+  }
+}