Fix Dockerfile verification: use generic transformers import check

EsmModel was reorganized in newer transformers versions.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Dockerfile

@@ -16,7 +16,7 @@ RUN pip install --no-cache-dir \
 
 # Verify installations
 RUN python -c "import torch; print(f'PyTorch: {torch.__version__}')" && \
-    python -c "from transformers import EsmModel; print('transformers: OK')" && \
+    python -c "import transformers; print(f'transformers: {transformers.__version__}')" && \
     python -c "import chai_lab; print('chai_lab: OK')" && \
     chai --help