feat: migrate from GitLab CI to Gitea Actions

- Update git remote to git.unbound.se
- Add Gitea workflows: ci.yaml, pre-commit.yaml, release.yaml, goreleaser.yaml
- Delete .gitlab-ci.yml
- Update Go module path to gitea.unbound.se/unboundsoftware/schemas
- Update all imports to new module path
- Update Docker registry to oci.unbound.se
- Update .goreleaser.yml for Gitea releases with internal cluster URL
- Remove GitLab CI linter from pre-commit config
- Use shared release workflow with tag_only for versioning

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

.gitea/workflows/pre-commit.yaml

@@ -0,0 +1,25 @@
+name: pre-commit
+permissions: read-all
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+jobs:
+  pre-commit:
+    runs-on: ubuntu-latest
+    env:
+      SKIP: no-commit-to-branch
+    steps:
+      - uses: actions/checkout@v6
+      - uses: actions/setup-go@v6
+        with:
+          go-version: 'stable'
+      - uses: actions/setup-python@v6
+        with:
+          python-version: '3.14'
+      - name: Install goimports
+        run: go install golang.org/x/tools/cmd/goimports@latest
+      - uses: pre-commit/action@v3.0.1