build(test): run unit tests with vitest and jsdom

Karma needed headless Chrome. Vitest with jsdom runs with no browser.
Lighthouse CI now gets Chrome from @puppeteer/browsers.
Two CSS font tests are dropped: jsdom does not apply real CSS.

README.md

@@ -87,7 +87,7 @@ Then open http://localhost:8080
 | `npm start` | Dev server |
 | `npm run build` | Production build |
 | `npm run watch` | Rebuild on change (development configuration) |
-| `npm test` | Unit tests (Karma + Jasmine, headless Chrome) |
+| `npm test` | Unit tests (Vitest + jsdom, no browser needed) |
 | `npm run lint` | ESLint over `src/**/*.ts` and `src/**/*.html` |
 | `npm run i18n:check` | Verifies `en.json` and `de.json` share the exact same keys |
 
@@ -104,7 +104,7 @@ Triggered on every push to `main` and on pull requests targeting `main`.
 
 1. Lint & type check — `npm run lint`
 2. i18n key sync — `npm run i18n:check`
-3. Unit tests — `npx ng test --watch=false`
+3. Unit tests — `npm test`
 4. Production build — `npx ng build --configuration production`
 5. Lighthouse audit — `npx lhci autorun` (performance & SEO)