fix(backtrack): use unlock action + github.token for merge steps

Agent-Logs-Url: https://github.com/petesramek/polyline-algorithm-csharp/sessions/55b3b887-da48-431d-8be6-18e274b6b370

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

Author: Copilot

.github/workflows/backtrack.yml

@@ -89,16 +89,16 @@ jobs:
 
       - name: 'Unlock preview branch for merge'
         if: ${{ steps.targets.outputs.preview-branch != '' }}
-        uses: './.github/actions/github/branch-protection/lock'
+        uses: './.github/actions/github/branch-protection/unlock'
         with:
           branch: ${{ steps.targets.outputs.preview-branch }}
           token: ${{ secrets.GH_ADMIN_TOKEN }}
-          lock-branch: 'false'
+          fail-on-error: 'true'
 
       - 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 }}
+          GH_TOKEN: ${{ github.token }}
         run: |
           gh api --method POST /repos/${{ github.repository }}/merges \
             --field base="${{ steps.targets.outputs.preview-branch }}" \
@@ -107,16 +107,16 @@ jobs:
 
       - name: 'Unlock develop branch for merge'
         if: ${{ steps.check-develop.outputs.exists == 'true' }}
-        uses: './.github/actions/github/branch-protection/lock'
+        uses: './.github/actions/github/branch-protection/unlock'
         with:
           branch: ${{ steps.targets.outputs.develop-branch }}
           token: ${{ secrets.GH_ADMIN_TOKEN }}
-          lock-branch: 'false'
+          fail-on-error: 'true'
 
       - 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 }}
+          GH_TOKEN: ${{ github.token }}
         run: |
           gh api --method POST /repos/${{ github.repository }}/merges \
             --field base="${{ steps.targets.outputs.develop-branch }}" \