docs: Add comprehensive Windows WSL2 setup guide

[wuttechadmin]

• Add detailed SETUP_WINDOWS_WSL2.md with step-by-step instructions
• Include WSL2 environment setup, CUDA installation, and dependency management
• Covers troubleshooting common issues and performance optimization
• Update main README to reference Windows setup guide
• Tested and verified on Windows 11 with Ubuntu 24.04 WSL2 and RTX 3050 Ti

This enables Windows users to successfully run HRM with CUDA support, resolving compilation issues with FlashAttention and CUDA extensions that occur in native Windows environments.

[TKoodi]

Look a like this document is ChatGPT generated. Is is missing details and version numbers to get system up and running.

I try to: CUDA Toolkit 12.9.0 and Pytoch Stable (2.8.0) pip version. After trying fighting it one day i still cannot install flash-attn.