feat: add stock indicators route and Alpaca account info

- New /stocks route with StockViewer component
- New /api/indicators endpoint with SMA, EMA, RSI, MACD
- New /api/alpaca/account endpoint
- AlpacaAccountInfo component on home page
- Indicator calculation utilities
- Tests for utilities and components
- Vite proxy config for /api

app/components/__tests__/AlpacaAccountInfo.test.tsx

@@ -0,0 +1,39 @@
+/// <reference types="vitest" />
+import { describe, it, expect, vi } from "vitest";
+import { render, screen, waitFor } from "@testing-library/react";
+import AlpacaAccountInfo from "../AlpacaAccountInfo";
+
+describe("AlpacaAccountInfo", () => {
+  it("displays account info after loading", async () => {
+    const mockFetch = vi.fn().mockResolvedValue({
+      ok: true,
+      json: async () => ({
+        cash: 12345.67,
+        buying_power: 8000.0,
+        portfolio_value: 25000.0,
+      }),
+    });
+    globalThis.fetch = mockFetch;
+
+    render(<AlpacaAccountInfo />);
+
+    await waitFor(() => {
+      expect(screen.getByText(/Alpaca Account/i)).toBeInTheDocument();
+    });
+    // Use regex to match number regardless of locale decimal separator
+    expect(screen.getByText(/\$12[\.,]345/)).toBeInTheDocument();
+    expect(screen.getByText(/\$8[\.,]000/)).toBeInTheDocument();
+    expect(screen.getByText(/\$25[\.,]000/)).toBeInTheDocument();
+  });
+
+  it("displays error when fetch fails", async () => {
+    const mockFetch = vi.fn().mockRejectedValue(new Error("Network error"));
+    globalThis.fetch = mockFetch;
+
+    render(<AlpacaAccountInfo />);
+
+    await waitFor(() => {
+      expect(screen.getByText(/Failed to load account info/i)).toBeInTheDocument();
+    });
+  });
+});