fix: improve E2E auth resilience and diagnostics (#33)

- Wait for Authentik popup to fully load (domcontentloaded + networkidle)
  before interacting with form elements
- Add explicit waitFor on username/password fields with 15s timeout
- Enable screenshot capture on test failure for better diagnostics
- Increase auth setup timeout to 60s to accommodate slow IdP responses

The auth setup was failing because the popup form elements weren't
ready when Playwright tried to fill them — this adds proper load
state waits between each interaction step.

Co-authored-by: gandalf-the-greybeard[bot] <gandalf-the-greybeard[bot]@users.noreply.github.com>

playwright.config.ts

@@ -11,9 +11,10 @@ export default defineConfig({
   use: {
     baseURL: process.env.HEADLAMP_URL || 'https://headlamp.animaniacs.farh.net',
     trace: 'on-first-retry',
+    screenshot: 'only-on-failure',
   },
   projects: [
-    { name: 'setup', testMatch: /auth\.setup\.ts/ },
+    { name: 'setup', testMatch: /auth\.setup\.ts/, timeout: 60_000 },
     {
       name: 'chromium',
       use: {