fix: remove unused function and fix lint warning

- Remove unused login helper in portfolio.spec.ts
- Add eslint-disable for useEffect in history page

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

frontend/e2e/portfolio.spec.ts

@@ -1,16 +1,5 @@
 import { test, expect } from "@playwright/test";
 
-// Helper to login before tests
-async function login(page: import("@playwright/test").Page) {
-  await page.goto("/login");
-  await page.fill('input[name="username"]', "testuser");
-  await page.fill('input[name="password"]', "testpassword");
-  await page.click('button[type="submit"]');
-
-  // Wait for redirect to dashboard or portfolio page
-  await page.waitForURL(/\/(portfolio)?$/);
-}
-
 test.describe("Portfolio", () => {
   test.beforeEach(async ({ page }) => {
     // Mock login - in real tests, use proper authentication

frontend/src/app/portfolio/[id]/history/page.tsx

@@ -89,6 +89,7 @@ export default function PortfolioHistoryPage() {
 
   useEffect(() => {
     fetchData();
+    // eslint-disable-next-line react-hooks/exhaustive-deps
   }, [portfolioId]);
 
   const handleCreateSnapshot = async () => {