chore: migrate from GitLab to Gitea

- Update module path from gitlab.com/unboundsoftware/storage to
  git.unbound.se/unboundsoftware/storage
- Update import examples in documentation (CLAUDE.md, README.md)
- Remove .gitlab-ci.yml (GitLab CI pipeline no longer needed)
- Remove gitlab-ci-linter pre-commit hook
- Update go-imports local path in pre-commit config

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/storage
 - repo: https://github.com/alessandrojcm/commitlint-pre-commit-hook
   rev: v9.23.0
   hooks:
@@ -30,7 +23,7 @@ repos:
   - id: go-imports
     args:
     - -local
-    - gitlab.com/unboundsoftware/storage
+    - git.unbound.se/unboundsoftware/storage
 - repo: https://github.com/lietu/go-pre-commit
   rev: v1.0.0
   hooks: