chore: migrate from Gitea to GitHub Actions exclusively

Remove Gitea workflows and consolidate to GitHub Actions as the single
CI/CD platform. GitHub is now the sole source of truth for the project.

Changes:
- Remove .gitea/workflows/ directory entirely
  - ai-review.yaml (Gitea-specific, not migrating)
  - e2e.yaml (replaced by .github/workflows/e2e.yaml)
  - release.yaml (already exists at .github/workflows/release.yaml)
- Migrate .gitea/workflows/ci.yaml → .github/workflows/ci.yaml
  - Add unit tests to CI workflow
  - Use Node.js 20 with npm caching
  - Add 10-minute timeout

GitHub Actions Workflows:
- ci.yaml: Lint, type-check, format-check, build, test
- e2e.yaml: End-to-end Playwright tests
- release.yaml: Build tarball, create GitHub release, update ArtifactHub metadata

Repository Setup:
- Single remote: https://github.com/cpfarhood/headlamp-polaris-plugin
- All development, CI/CD, and releases happen on GitHub
- ArtifactHub pulls releases from GitHub every 30 minutes

Generated with [Claude Code](https://claude.ai/code)
via [Happy](https://happy.engineering)

Co-Authored-By: Claude <noreply@anthropic.com>
Co-Authored-By: Happy <yesreply@happy.engineering>

.gitea/workflows/e2e.yaml

@@ -1,28 +0,0 @@
-name: E2E
-
-on:
-  push:
-    branches:
-      - main
-  pull_request:
-
-jobs:
-  e2e:
-    runs-on: ubuntu-latest
-    container: node:20
-    steps:
-      - name: Checkout
-        uses: actions/checkout@v4
-
-      - name: Install dependencies
-        run: npm ci
-
-      - name: Install Chromium
-        run: npx playwright install --with-deps chromium
-
-      - name: Run E2E smoke tests
-        env:
-          HEADLAMP_URL: https://headlamp.animaniacs.farh.net
-          AUTHENTIK_USERNAME: ${{ secrets.AUTHENTIK_USERNAME }}
-          AUTHENTIK_PASSWORD: ${{ secrets.AUTHENTIK_PASSWORD }}
-        run: npx playwright test