fix: lock branch during backtrack, use REST API merge to bypass git push 403

Agent-Logs-Url: https://github.com/petesramek/polyline-algorithm-csharp/sessions/0bdd21ff-4b77-41fb-9a82-83016fb91c1c

Co-authored-by: petesramek <2333452+petesramek@users.noreply.github.com>

Author: Copilot

.github/workflows/backtrack.yml

@@ -61,36 +61,33 @@ jobs:
             echo "::warning::Develop branch '${{ steps.targets.outputs.develop-branch }}' not found, skipping backtrack."
           fi
 
-      - name: 'Unlock develop branch'
-        id: unlock-develop
+      - name: 'Lock develop branch'
+        id: lock-develop
         if: ${{ steps.check-develop.outputs.exists == 'true' }}
-        uses: './.github/actions/github/branch-protection/unlock'
+        uses: './.github/actions/github/branch-protection/lock'
         with:
           branch: ${{ steps.targets.outputs.develop-branch }}
           token: ${{ secrets.GH_ADMIN_TOKEN }}
 
       - name: 'Backtrack: merge ${{ github.base_ref }} into ${{ steps.targets.outputs.preview-branch }}'
         if: ${{ steps.targets.outputs.preview-branch != '' }}
+        env:
+          GH_TOKEN: ${{ secrets.GH_ADMIN_TOKEN }}
         run: |
-          git fetch origin
-          git checkout -B ${{ steps.targets.outputs.preview-branch }} origin/${{ steps.targets.outputs.preview-branch }}
-          git merge --no-ff origin/${{ github.base_ref }} -m "Backtrack: merge ${{ github.base_ref }} into ${{ steps.targets.outputs.preview-branch }}"
-          git push origin ${{ steps.targets.outputs.preview-branch }}
+          gh api --method POST /repos/${{ github.repository }}/merges \
+            --field base="${{ steps.targets.outputs.preview-branch }}" \
+            --field head="${{ github.base_ref }}" \
+            --field commit_message="Backtrack: merge ${{ github.base_ref }} into ${{ steps.targets.outputs.preview-branch }}"
 
       - name: 'Backtrack: merge ${{ steps.targets.outputs.merge-source }} into ${{ steps.targets.outputs.develop-branch }}'
         if: ${{ steps.check-develop.outputs.exists == 'true' }}
+        env:
+          GH_TOKEN: ${{ secrets.GH_ADMIN_TOKEN }}
         run: |
-          git fetch origin
-          git checkout -B ${{ steps.targets.outputs.develop-branch }} origin/${{ steps.targets.outputs.develop-branch }}
-          git merge --no-ff origin/${{ steps.targets.outputs.merge-source }} -m "Backtrack: merge ${{ steps.targets.outputs.merge-source }} into ${{ steps.targets.outputs.develop-branch }}"
-          git push origin ${{ steps.targets.outputs.develop-branch }}
-
-      - name: 'Lock develop branch'
-        if: ${{ always() && steps.unlock-develop.outcome != 'skipped' }}
-        uses: './.github/actions/github/branch-protection/lock'
-        with:
-          branch: ${{ steps.targets.outputs.develop-branch }}
-          token: ${{ secrets.GH_ADMIN_TOKEN }}
+          gh api --method POST /repos/${{ github.repository }}/merges \
+            --field base="${{ steps.targets.outputs.develop-branch }}" \
+            --field head="${{ steps.targets.outputs.merge-source }}" \
+            --field commit_message="Backtrack: merge ${{ steps.targets.outputs.merge-source }} into ${{ steps.targets.outputs.develop-branch }}"
 
       - name: 'Write backtrack summary'
         if: ${{ always() }}