(test) add python script to compare goldens

.github/workflows/dart.yml

@@ -37,12 +37,14 @@ jobs:
       - name: Download golden images
         uses: actions/download-artifact@v4
         with:
-          name: golden-images-f0cf20d904f67e03c7ae247d18287b7f8a053cd2
-          path: ./golden-downloads
+          name: golden-images-${{ github.sha }}
+          path: ./thermion_dart/test/golden-downloads
       - name: Install Python dependencies
         run: |
           python -m pip install --upgrade pip
           pip install Pillow numpy
+      - name: Compare golden images
+        run: cd thermion_dart/test && python compare_goldens.py
       - name: Upload logs
         if: failure() || steps.build.outcome == 'failure'
         uses: actions/upload-artifact@v4