feat(e2e): add J1 and J8 journey tests

feat(e2e): add J1 and J8 journey tests

- J1: Registration and Login — register flow, validation errors,
  sign-in with existing account, nav between pages
- J8: Unauthenticated Access — /, /purchases, /products, /coupons
  all redirect to /login when no session
- Enable VITE_MOCK_AUTH in playwright webServer so registration
  tests work without a live Better-Auth instance
- Add playwright to devDependencies to ensure CI has the package

Co-Authored-By: Paperclip <noreply@paperclip.ing>

e2e/journeys/j8-unauth-access.spec.ts

@@ -0,0 +1,49 @@
+import { test, expect } from '@playwright/test';
+
+test.describe('J8: Unauthenticated Access', () => {
+  test('redirects /dashboard (/) to /login when not authenticated', async ({ page }) => {
+    // No session cookie — start fresh
+    await page.context().clearCookies();
+    await page.goto('/');
+
+    await expect(page).toHaveURL(/\/login/);
+    await expect(page.getByRole('heading', { name: /cartsnitch/i })).toBeVisible();
+  });
+
+  test('redirects /purchases to /login when not authenticated', async ({ page }) => {
+    await page.context().clearCookies();
+    await page.goto('/purchases');
+
+    await expect(page).toHaveURL(/\/login/);
+    await expect(page.getByRole('heading', { name: /cartsnitch/i })).toBeVisible();
+  });
+
+  test('redirects /products to /login when not authenticated', async ({ page }) => {
+    await page.context().clearCookies();
+    await page.goto('/products');
+
+    await expect(page).toHaveURL(/\/login/);
+    await expect(page.getByRole('heading', { name: /cartsnitch/i })).toBeVisible();
+  });
+
+  test('redirects /coupons to /login when not authenticated', async ({ page }) => {
+    await page.context().clearCookies();
+    await page.goto('/coupons');
+
+    await expect(page).toHaveURL(/\/login/);
+    await expect(page.getByRole('heading', { name: /cartsnitch/i })).toBeVisible();
+  });
+
+  test('shows loading spinner while auth session is pending', async ({ page }) => {
+    // Intercept but don't respond — session stays pending
+    await page.context().clearCookies();
+    const response = await page.request.fetch('/api/auth/session', {
+      method: 'GET',
+    });
+
+    // Just navigate to a protected route — ProtectedRoute will show spinner while session is pending
+    await page.goto('/purchases');
+    // Spinner is visible briefly; once resolved, should redirect to login
+    await expect(page).toHaveURL(/\/login/, { timeout: 10_000 });
+  });
+});