docs: Add comprehensive WSL/Linux setup guide for cross-platform development

Added WSL_LINUX_SETUP_GUIDE.md to help transition from Windows-based
development to Linux-compatible workflow, ensuring compatibility with
claude.ai/code's Linux containers.

Guide includes:
- WSL2 installation and configuration
- Python 3.11+, Blender 4.2+, FFmpeg setup
- Cross-platform path handling best practices
- VS Code Remote-WSL integration
- Docker containerization for exact environment matching
- Common issues and solutions
- Development workflow recommendations

This addresses the Windows/Linux discrepancy identified during the
3D rendering and mascot geometry fixes in PR #13.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: michshat