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>

.pre-commit-config.yaml

@@ -10,13 +10,6 @@ repos:
     args:
     - --allow-multiple-documents
   - id: check-added-large-files
-- repo: https://gitlab.com/devopshq/gitlab-ci-linter
-  rev: v1.0.6
-  hooks:
-  - id: gitlab-ci-linter
-    args:
-    - --project
-    - unboundsoftware/schemas
 - repo: https://github.com/alessandrojcm/commitlint-pre-commit-hook
   rev: v9.24.0
   hooks:
@@ -30,7 +23,7 @@ repos:
   - id: go-imports
     args:
     - -local
-    - gitlab.com/unboundsoftware/schemas
+    - git.unbound.se/unboundsoftware/schemas
 - repo: https://github.com/lietu/go-pre-commit
   rev: v1.0.0
   hooks: