fix(ci): skip auto-tag when no new commits since latest tag

[drew]

Summary

Prevents the nightly release-auto-tag workflow from creating redundant patch tags when there are no new commits since the latest tag.

Changes

• Added a git rev-list check after finding the latest tag to count commits between it and HEAD
• If the count is zero, sets a skip output and exits early
• Added if: steps.version.outputs.skip != 'true' guards on the "Create and push tag" and "Trigger Release Tag workflow" steps

Testing

• mise run pre-commit passes
• Unit tests added/updated
• E2E tests added/updated (if applicable)

Checklist

• Follows Conventional Commits
• Commits are signed off (DCO)
• Architecture docs updated (if applicable)