Fix HuggingFace cache directory permissions

- Set HF_HOME, TRANSFORMERS_CACHE, HF_DATASETS_CACHE to writable temp directory
- Prevent PermissionError when downloading SmolVLM2 model to /.cache
- Configure cache directories before importing HF libraries
- Fix model download issues in Docker environment

highlights_api.py

@@ -4,13 +4,21 @@ FastAPI Wrapper for Audio-Enhanced Video Highlights
 Converts your SmolVLM2 + Whisper system into a web API for Android apps
 """
 
+import os
+import tempfile
+
+# Set cache directories to writable locations before importing HF libraries
+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
+
 from fastapi import FastAPI, UploadFile, File, HTTPException, BackgroundTasks
 from fastapi.responses import FileResponse, JSONResponse
 from fastapi.middleware.cors import CORSMiddleware
 from pydantic import BaseModel
-import os
 import sys
-import tempfile
 import uuid
 import json
 import asyncio