debug: capture Docker build logs in step summary for Void diagnosis

Author: porus

.github/workflows/test.yml

@@ -33,7 +33,20 @@ jobs:
       - uses: actions/checkout@v4
 
       - name: Build Docker image
-        run: docker build -t lsg-test:${{ matrix.distro }} -f tests/docker/Dockerfile.${{ matrix.distro }} .
+        run: |
+          docker build -t lsg-test:${{ matrix.distro }} -f tests/docker/Dockerfile.${{ matrix.distro }} . 2>&1 | tee docker-build.log
+          echo "BUILD_EXIT_CODE=${PIPESTATUS[0]}" >> $GITHUB_ENV
+        continue-on-error: true
+
+      - name: Check build result
+        run: |
+          if [ "$BUILD_EXIT_CODE" != "0" ]; then
+            echo "## ❌ Docker build failed for ${{ matrix.distro }}" >> $GITHUB_STEP_SUMMARY
+            echo '```' >> $GITHUB_STEP_SUMMARY
+            tail -50 docker-build.log >> $GITHUB_STEP_SUMMARY
+            echo '```' >> $GITHUB_STEP_SUMMARY
+            exit 1
+          fi
 
       - name: Run tests
         run: python3 tests/runner.py --distro ${{ matrix.distro }}