chore: update ports to 4000-range (4000/4001)

services/backend/src/e2e.test.ts

@@ -1,10 +1,10 @@
 /**
  * E2E API tests — runs against a running backend instance.
- * Usage: API_BASE=http://localhost:3001 vitest run
+ * Usage: API_BASE=http://localhost:4001 vitest run
  */
 import { describe, expect, it } from "vitest";
 
-const BASE = process.env.API_BASE ?? "http://localhost:3001/api";
+const BASE = process.env.API_BASE ?? "http://localhost:4001/api";
 
 async function api(path: string, init?: RequestInit) {
   const res = await fetch(`${BASE}${path}`, {