Add full test suite with unit, integration, and E2E smoke tests.

Introduce test.bat orchestrating Go/Vitest/Playwright phases, expand coverage across server, agent, and dashboard, and document in tests/README.md.

server/web/src/api/auth.test.ts

@@ -0,0 +1,26 @@
+/**
+ * @vitest-environment happy-dom
+ */
+import { beforeEach, describe, expect, it } from 'vitest';
+import { authHeaders, clearStoredAuth, getStoredAuth, setStoredAuth } from '../api/auth';
+
+describe('auth session helpers', () => {
+  beforeEach(() => {
+    sessionStorage.clear();
+  });
+
+  it('stores and retrieves basic token', () => {
+    setStoredAuth('drjones', 'secret');
+    expect(getStoredAuth()).toBe(btoa('drjones:secret'));
+  });
+
+  it('builds Authorization header when logged in', () => {
+    setStoredAuth('user', 'pass');
+    expect(authHeaders()).toEqual({ Authorization: `Basic ${btoa('user:pass')}` });
+  });
+
+  it('returns empty headers when logged out', () => {
+    clearStoredAuth();
+    expect(authHeaders()).toEqual({});
+  });
+});