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>

eslint.config.js

@@ -22,10 +22,16 @@ export default [
     },
   },
   {
-    files: ['server/**/*.js', 'scripts/**/*.mjs', 'vite.config.js', 'eslint.config.js', 'postcss.config.js', 'tailwind.config.js'],
+    files: ['server/**/*.js', 'scripts/**/*.mjs', 'vite.config.js', 'playwright.config.js', 'eslint.config.js', 'postcss.config.js', 'tailwind.config.js'],
     languageOptions: { ecmaVersion: 'latest', sourceType: 'module', globals: { ...globals.node } },
     rules: { 'no-unused-vars': ['warn', { argsIgnorePattern: '^_', caughtErrors: 'none' }], 'no-empty': ['error', { allowEmptyCatch: true }] },
   },
+  {
+    // Playwright tests run in Node but hand functions to the browser page, which use browser globals
+    files: ['e2e/**/*.js'],
+    languageOptions: { ecmaVersion: 'latest', sourceType: 'module', globals: { ...globals.node, ...globals.browser } },
+    rules: { 'no-unused-vars': ['warn', { argsIgnorePattern: '^_', caughtErrors: 'none' }] },
+  },
   {
     files: ['**/*.test.{js,jsx}', 'src/setupTests.js', 'src/test/**'],
     languageOptions: { globals: { ...globals.browser, ...globals.node, vi: 'readonly' } },