Publish `common-templates` library chart to GitLab charts repository
## Objective
Publish the `common-templates` library chart to the GitLab charts Git repository and establish the publishing workflow.
## Context
The library chart needs to be published in a location that is accessible to both the GitLab Helm chart and Runway standalone service charts. Publishing to the GitLab charts repository ensures discoverability and aligns with existing GitLab chart conventions.
## Tasks
- [x] Set up CI/CD pipeline for `common-templates` repository
- [x] Configure chart packaging and publishing workflow
- [x] Publish initial version (v1.0.0) to GitLab charts repository
- [x] Verify chart is accessible via OCI registry or Git repository
- [x] Document publishing process for future updates
- [x] Set up automated releases (e.g., via semantic-release or similar)
- [x] The Semantic Release PrAT has push permissions on `main`
## Success Criteria
- [x] `common-templates` v1.0.0 is published and accessible
- [x] CI/CD pipeline successfully packages and publishes the chart
- [x] Documentation exists for making future releases
- [x] Chart can be referenced as a dependency by other charts
## Dependencies
- Requires completion of #773 (extract templates)
## Related
- Parent Epic: &34
issue