Comprehensive fix for HuggingFace cache directory permissions

- Add cache directory environment variables to smolvlm2_handler.py
- Ensure cache directories are set before any transformers import
- Fix model download permission errors at the source
- Prevent PermissionError when downloading SmolVLM2 models

src/smolvlm2_handler.py

@@ -4,6 +4,17 @@ SmolVLM2 Model Handler
 Handles loading and inference with SmolVLM2-1.7B-Instruct model
 """
 
+import os
+import tempfile
+
+# Set cache directories to writable locations before importing transformers
+if 'HF_HOME' not in os.environ:
+    CACHE_DIR = tempfile.mkdtemp(prefix="hf_cache_")
+    os.environ['HF_HOME'] = CACHE_DIR
+    os.environ['TRANSFORMERS_CACHE'] = CACHE_DIR
+    os.environ['HF_DATASETS_CACHE'] = CACHE_DIR
+    os.environ['TORCH_HOME'] = CACHE_DIR
+
 import torch
 from transformers import AutoModelForImageTextToText, AutoProcessor
 from PIL import Image