Real-browser tests (Playwright) and housekeeping

- npm run test:e2e builds the app, runs it on port 3101 with an empty throwaway
  database and drives Chrome (the installed one; no browser download) through
  notes and the paste check, the daily five minutes and weekly recall,
  translation compare (Bible text faked), and two-screen presenting.
- Vitest skips e2e/; ESLint knows the e2e folder and playwright.config.js.
- .gitignore: the local demo video, Playwright output and sign-in file.
- README and TODO describe the browser tests and what CI still needs.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

.gitignore

@@ -13,3 +13,11 @@ coverage/
 .env
 .session-secret
 server/data/backups/
+
+# Playwright
+e2e/.auth.json
+test-results/
+playwright-report/
+
+# a local demo video, not part of the app
+demo/