Improve USD export and Isaac Sim repair pipeline

Author: nepfaff

.github/workflows/integration_test.yaml

@@ -69,3 +69,38 @@ jobs:
             .testmondata-shm
             .testmondata-wal
           key: ${{ steps.cache-testmon-restore.outputs.cache-primary-key }}
+
+  usd-export-test:
+    runs-on: ubuntu-latest
+    timeout-minutes: 30
+
+    env:
+      SCENESMITH_RUN_USD_EXPORT_TESTS: "1"
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Install uv
+        uses: astral-sh/setup-uv@v6
+        with:
+          version: "0.7.8"
+          enable-cache: true
+
+      - name: Set up Python
+        uses: actions/setup-python@v5
+        with:
+          python-version-file: ".python-version"
+
+      - name: Install system dependencies
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y libegl1
+
+      - name: Set up MuJoCo/USD export environment
+        run: bash scripts/setup_mujoco_export.sh
+
+      - name: Run USD export integration test
+        run: |
+          source .mujoco_venv/bin/activate
+          python -m unittest tests.integration.test_usd_export_pipeline