Add Vitest integration tests for website group invitation functions

Tests createGroup, createGroupInvitation, and acceptGroupInvitation
end-to-end against the local Supabase instance. Also fixes a bug where
createGroupInvitation was JSON.stringify-ing the JSONB payload, causing
accept_group_invitation to silently return false.

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

Author: maparent

apps/website/package.json

@@ -11,7 +11,8 @@
     "start": "next start",
     "lint": "eslint .",
     "lint:fix": "eslint . --fix",
-    "check-types": "tsc --noEmit --skipLibCheck"
+    "check-types": "tsc --noEmit --skipLibCheck",
+    "test:integration": "vitest run --config vitest.integration.config.ts"
   },
   "dependencies": {
     "@repo/database": "workspace:*",
@@ -35,6 +36,8 @@
   },
   "devDependencies": {
     "@repo/eslint-config": "workspace:*",
+    "dotenv": "^16.0.0",
+    "vitest": "^4.0.0",
     "@repo/tailwind-config": "workspace:*",
     "@repo/types": "workspace:*",
     "@repo/typescript-config": "workspace:*",

apps/website/test/setup.integration.ts

@@ -0,0 +1,12 @@
+import dotenv from "dotenv";
+import path from "path";
+
+dotenv.config({
+  path: path.resolve(__dirname, "../../../packages/database/.env.local"),
+});
+
+if (process.env.SUPABASE_URL?.includes("supabase.co")) {
+  throw new Error(
+    "Integration tests must not run against production Supabase. Check SUPABASE_URL.",
+  );
+}

apps/website/vitest.integration.config.ts

@@ -0,0 +1,25 @@
+import { defineConfig } from "vitest/config";
+import path from "path";
+
+export default defineConfig({
+  test: {
+    environment: "node",
+    include: ["test/integration/**/*.test.ts"],
+    exclude: ["scripts/**"],
+    setupFiles: ["test/setup.integration.ts"],
+    sequence: { concurrent: false },
+    pool: "forks",
+    maxWorkers: 1,
+    tags: [
+      {
+        name: "database",
+        description: "Tests requiring the database",
+      },
+    ],
+  },
+  resolve: {
+    alias: {
+      "~": path.resolve(__dirname, "app"),
+    },
+  },
+});