[leaderboard] add stub

apps/leaderboard/vitest.config.ts

@@ -0,0 +1,15 @@
+import { cloudflareTest } from '@cloudflare/vitest-pool-workers'
+import { defineConfig } from 'vitest/config'
+
+export default defineConfig({
+	plugins: [
+		cloudflareTest({
+			wrangler: { configPath: `${__dirname}/wrangler.jsonc` },
+			miniflare: {
+				bindings: {
+					ENVIRONMENT: 'VITEST',
+				},
+			},
+		}),
+	],
+})