fix: backtrack workflow - only lock source branch, not merge targets

Agent-Logs-Url: https://github.com/petesramek/polyline-algorithm-csharp/sessions/ad3c6a94-dc51-4ac7-996b-a56f710a69c7

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

Author: Copilot

.github/workflows/backtrack.yml

@@ -69,24 +69,6 @@ jobs:
           token: ${{ secrets.GH_ADMIN_TOKEN }}
           lock-branch: 'true'
 
-      - name: 'Lock preview branch'
-        id: lock-preview
-        if: ${{ steps.targets.outputs.preview-branch != '' }}
-        uses: './.github/actions/github/branch-protection/lock'
-        with:
-          branch: ${{ steps.targets.outputs.preview-branch }}
-          token: ${{ secrets.GH_ADMIN_TOKEN }}
-          lock-branch: 'true'
-
-      - name: 'Lock develop branch'
-        id: lock-develop
-        if: ${{ steps.check-develop.outputs.exists == 'true' }}
-        uses: './.github/actions/github/branch-protection/lock'
-        with:
-          branch: ${{ steps.targets.outputs.develop-branch }}
-          token: ${{ secrets.GH_ADMIN_TOKEN }}
-          lock-branch: 'true'
-
       - name: 'Backtrack: merge ${{ github.base_ref }} into ${{ steps.targets.outputs.preview-branch }}'
         if: ${{ steps.targets.outputs.preview-branch != '' }}
         env:
@@ -115,22 +97,6 @@ jobs:
           token: ${{ secrets.GH_ADMIN_TOKEN }}
           lock-branch: 'false'
 
-      - name: 'Restore protection: preview branch'
-        if: ${{ always() && steps.lock-preview.outcome == 'success' }}
-        uses: './.github/actions/github/branch-protection/lock'
-        with:
-          branch: ${{ steps.targets.outputs.preview-branch }}
-          token: ${{ secrets.GH_ADMIN_TOKEN }}
-          lock-branch: 'false'
-
-      - name: 'Restore protection: develop branch'
-        if: ${{ always() && steps.lock-develop.outcome == 'success' }}
-        uses: './.github/actions/github/branch-protection/lock'
-        with:
-          branch: ${{ steps.targets.outputs.develop-branch }}
-          token: ${{ secrets.GH_ADMIN_TOKEN }}
-          lock-branch: 'false'
-
       - name: 'Write backtrack summary'
         if: ${{ always() }}
         run: |