fix(ci): prevent staging workflow from publishing stable versions with rc tags

[pasevin]

Problem

Fixed the race condition where the staging workflow would incorrectly publish stable versions (e.g., 0.4.0, 0.5.0) with 'rc' tags on npm instead of 'latest' tags.

Root Cause

When 'Version Packages' PRs were merged:

1. Package.json versions were updated to stable versions (0.4.0, etc.)
2. Both staging and release workflows triggered simultaneously
3. Staging workflow ran changeset version --snapshot rc → 'No unreleased changesets found'
4. Staging workflow fell back to publishing existing stable versions with --tag rc
5. Release workflow tried to publish but npm said 'already exists'

Solution

• Added changeset detection to skip RC publishing when no pending changesets exist
• Added concurrency controls to prevent staging/release workflow conflicts
• Only publish RC snapshots when there are actual changes to test

This ensures:

• ✅ Staging workflow only publishes when there are changes to test
• ✅ Release workflow can properly publish stable versions with 'latest' tags
• ✅ No more stable versions incorrectly tagged as 'rc' on npm

Files Changed

• : Added changeset detection and concurrency controls
• : Updated concurrency group naming for coordination

Testing

The fix has been tested locally and the logic prevents the race condition scenario that caused the npm tagging issue.