Skip branch sync when fork is ahead of upstream

[Copilot]

The sync workflow was force-pushing upstream state onto fork branches unconditionally when commits diverged, overwriting any fork-only commits.

• Added a git merge-base --is-ancestor check: if the upstream commit is an ancestor of the fork's commit, the fork is strictly ahead and the sync is skipped
• Branch is counted as skipped with a descriptive log message

# If the fork branch is ahead of upstream (upstream is an ancestor of origin), skip.
if git merge-base --is-ancestor "$upstream_sha" "$origin_sha"; then
  echo "Branch '${branch}' in fork is ahead of upstream – skipping."
  skipped=$((skipped + 1))
  continue
fi

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[codecov]

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