fix(ci): upgrade to build-push-action@v6, disable sbom

- Upgrade docker/build-push-action from v5 to v6
- Add sbom: false alongside provenance: false
- Update registry URL to internal domain

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

CHANGELOG.md

@@ -7,6 +7,12 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [1.2.3] - 2025-12-14
+
+### Fixed
+
+- **CI**: Upgrade to build-push-action@v6, disable provenance and sbom for Gitea registry
+
 ## [1.2.2] - 2025-12-13
 
 ### Fixed