…is set (#2355)

* Initial plan

* Add orchestration ID support to git user-agent

Co-authored-by: TingluoHuang <[email protected]>

* Apply suggestion from @Copilot

Co-authored-by: Copilot <[email protected]>

* Improve tests to verify user-agent content and handle empty sanitized IDs

Co-authored-by: TingluoHuang <[email protected]>

* Simplify orchestration ID validation to accept any non-empty sanitized value

Co-authored-by: TingluoHuang <[email protected]>

* Remove test for orchestration ID with only invalid characters

Co-authored-by: TingluoHuang <[email protected]>

---------

Co-authored-by: copilot-swe-agent[bot] <[email protected]>
Co-authored-by: TingluoHuang <[email protected]>
Co-authored-by: Tingluo Huang <[email protected]>
Co-authored-by: Copilot <[email protected]>

This PR fixes several issues with tag handling in the checkout action:

1. fetch-tags: true now works (fixes #1471)
   - Tags refspec is now included in getRefSpec() when fetchTags=true
   - Previously tags were only fetched during a separate fetch that was
     overwritten by the main fetch

2. Tag checkout preserves annotations (fixes #290)
   - Tags are fetched via refspec (+refs/tags/*:refs/tags/*) instead of
     --tags flag
   - This fetches the actual tag objects, preserving annotations

3. Tag checkout with fetch-tags: true no longer fails (fixes #1467)
   - When checking out a tag with fetchTags=true, only the wildcard
     refspec is used (specific tag refspec is redundant)

Changes:
- src/ref-helper.ts: getRefSpec() now accepts fetchTags parameter and
  prepends tags refspec when true
- src/git-command-manager.ts: fetch() simplified to always use --no-tags,
  tags are fetched explicitly via refspec
- src/git-source-provider.ts: passes fetchTags to getRefSpec()
- Added E2E test for fetch-tags option

Related #1471, #1467, #290