Fix: Pre-download models in Dockerfile to avoid runtime hang

Root cause analysis:
- preload_from_hub ignores HF_HOME (documented limitation)
- Previous approach caused permission conflicts → fallback to /tmp
- local_files_only=True + no models in /tmp = startup failure

Solution (best practice from research):
- Manually download models in Dockerfile to default ~/.cache location
- Download as 'user' to avoid permission issues
- Keep local_files_only=True (models already cached)
- Build logs show download progress (transparent to user)

Changes:
- README.md: Remove preload_from_hub (has limitations)
- Dockerfile: Add manual model download step (lines 100-119)
- All models download during build → instant runtime startup

Benefits:
✅ Build logs show download progress (no "hanging" confusion)
✅ Runtime startup is instant (models already in image)
✅ No permission conflicts (consistent user ownership)
✅ Works on free tier (no /data persistent storage needed)

Updated: README.md

README.md

@@ -7,9 +7,6 @@ sdk: docker
 app_port: 7860
 pinned: false
 license: mit
-preload_from_hub:
-  - 0xZohar/object-assembler-models
-  - openai/clip-vit-base-patch32
 env:
   HF_HOME: /home/user/.cache/huggingface
   HF_HUB_CACHE: /home/user/.cache/huggingface/hub