fix: Resolve PIL/scipy import issue with Python version-specific PYTHONPATH

Major fixes for rigged_3d pipeline:

1. Fixed PIL/scipy imports by setting PYTHONPATH to Python 3.10 packages
   - Issue: main.py (Python 3.13) was setting Python 3.13's site-packages
   - Blender uses Python 3.10, needs Python 3.10's packages
   - Solution: Explicitly set PYTHONPATH to Python310/site-packages
   - Files: main.py:246-265

2. Enhanced import debugging and pre-loading
   - Added pre-load attempts in blender_script.py with detailed logging
   - Added sys.modules checks in auto_rigging.py
   - Files: blender_script.py:32-56, auto_rigging.py:44-77

3. Fixed render engine enum for Blender 4.0+
   - Changed EEVEE -> BLENDER_EEVEE
   - File: demo_reel/config_rigged_3d.yaml:19

4. Added comprehensive test scripts
   - test_pil_import.py: Standalone PIL/scipy import test
   - test_auto_rigging_direct.py: Direct rigging test (Phase 1)
   - test_full_rigging.py: Full 5-phase rigging test

5. Documentation
   - SESSION_SUMMARY_2025-11-09.md: Complete session summary
   - Detailed troubleshooting steps and root cause analysis

Status:
✅ Variable scope error fixed (sys import)
✅ Render engine enum fixed (BLENDER_EEVEE)
✅ Error handling added with try-except blocks
✅ PYTHONPATH set for correct Python version
🔄 Testing in progress for PIL/scipy fix

Expected outcome:
- 202-vertex fox mesh instead of 482-vertex fallback sphere
- Proper image-to-mesh conversion with contour detection
- Full auto-rigging pipeline with real image processing

Author: michshat