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/app/globals.css

@@ -1745,7 +1745,7 @@ details[open] > summary .details-open\:rotate-180 {
 /* Input focus glow */
 .input-glow:focus {
 	outline: none;
-	border-color: var(--color-primary) !important;
+	border-color: var(--color-primary);
 	box-shadow:
 		0 0 0 3px color-mix(in srgb, var(--color-primary) 15%, transparent),
 		0 0 20px color-mix(in srgb, var(--color-primary) 10%, transparent);