chore: improve tooling, linting, testing, and CI

- Add LICENSE file (CC BY-NC-SA 4.0)
- Add .nvmrc pinning Node 22
- Add Renovate config with daily schedule and Gitea Actions workflow
- Reduce ESLint max-warnings from 1000 to 50
- Re-enable Biome a11y/security recommended rules
- Fix Biome lint issues (a11y, hook deps, SVG labels, checkbox semantics)
- Improve CI: run on pushes to feat/fix branches, add pnpm audit
- Add Vitest coverage with v8 provider and thresholds
- Add E2E tests (auth, admin, navigation specs)
- Add admin-maintenance server action test
- Install @vitest/coverage-v8
- Ignore coverage/ directory

src/components/pwa-register.tsx

@@ -15,7 +15,7 @@ export function PwaRegister() {
 			}
 		});
 
-		navigator.serviceWorker.register("/sw.js?" + SW_VERSION).catch(() => {});
+		navigator.serviceWorker.register(`/sw.js?${SW_VERSION}`).catch(() => {});
 	}, []);
 	return null;
 }