ci: compare warnings with main branch

.github/workflows/zxc-code-style.yaml

@@ -80,4 +80,36 @@ jobs:
             npm ci
 
       - name: Check Code Style
-        run: task check
+        run: |
+          task check
+          mv eslint.log eslint-branch.log || true
+
+      - name: Compare warnings with target branch
+        if: ${{ github.event_name == 'pull_request' }}
+        run: |
+          get_warnings() {
+            file="$1"
+            if [ -f "$file" ]; then
+              # Use awk to find the line containing "problems" and print the token before "warnings"
+              awk -F'[(), ]+' '/problems/ { for(i=1;i<=NF;i++) if($i=="warnings") print $(i-1) }' "$file" | tail -n1
+            else
+              echo 0
+            fi
+          }
+          # Determine the PR target (base) branch
+          target_branch="${{ github.event.pull_request.base.ref }}"
+          echo "Target branch: $target_branch"
+          # Fetch and check out the target branch from origin
+          git fetch origin "$target_branch":"$target_branch"
+          git checkout "$target_branch"
+          task check
+          branch_warnings=$(get_warnings eslint-branch.log)
+          target_warnings=$(get_warnings eslint.log)
+          echo "Warnings on branch: $branch_warnings"
+          echo "Warnings on target ($target_branch): $target_warnings"
+          if [ "$branch_warnings" -gt "$target_warnings" ]; then
+            echo "✘ Warnings have increased from $target_warnings to $branch_warnings"
+            exit 1
+          else
+            echo "✔ Warnings have not increased"
+          fi