chore: install Playwright and add E2E test configuration

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

tests/middleware/rateLimit.test.ts

@@ -1,6 +1,9 @@
 import { beforeEach, describe, expect, it } from "bun:test";
 import { Hono } from "hono";
-import { _resetForTesting, rateLimit } from "../../src/server/middleware/rateLimit";
+import {
+	_resetForTesting,
+	rateLimit,
+} from "../../src/server/middleware/rateLimit";
 
 function createApp() {
 	const app = new Hono();