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();

tests/routes/params.test.ts

@@ -48,7 +48,9 @@ describe("Invalid ID parameter handling", () => {
 
 	describe("categories", () => {
 		it("DELETE /api/categories/abc returns 400", async () => {
-			const res = await app.request("/api/categories/abc", { method: "DELETE" });
+			const res = await app.request("/api/categories/abc", {
+				method: "DELETE",
+			});
 			expect(res.status).toBe(400);
 		});
 	});