feat: add React UI for rpm.lair.cafe

- Vite + React + SWC + TypeScript SPA with react-router and
  react-bootstrap
- Dark/light/system theme with Bootstrap 5.3 data-bs-theme
- Home page with repo setup instructions and copyable code blocks
- Package list and detail pages driven by packages.json
- Python script to generate packages.json from repodata XML
- Nginx config updated for SPA fallback, asset caching, removed
  autoindex
- New deploy-ui workflow triggered on ui/ or nginx config changes,
  requires runners with nvm label
- packages.json generation added to publish job after createrepo_c
- Runner setup docs for nvm and sequoia-sq added to readme

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.gitea/workflows/build-release.yml

@@ -190,3 +190,12 @@ jobs:
         run: |
           ssh "gitea_ci@${RPM_REPO_HOST}" \
             "cd /var/www/rpm/fedora/${{ matrix.fedora_version }}/x86_64 && createrepo_c --update ."
+
+      - name: Generate packages.json
+        run: |
+          scp script/generate-packages-json.py "gitea_ci@${RPM_REPO_HOST}:/tmp/"
+          ssh "gitea_ci@${RPM_REPO_HOST}" \
+            "python3 /tmp/generate-packages-json.py \
+              --repodata-dir /var/www/rpm/fedora/${{ matrix.fedora_version }}/x86_64/repodata \
+              --output /var/www/rpm/fedora/${{ matrix.fedora_version }}/x86_64/packages.json \
+              --base-url https://rpm.lair.cafe/fedora/${{ matrix.fedora_version }}/x86_64"