[Win] Deployment issue and setup improvement proposal

## 📌 Summary

This issue is to track the setup and deployment process of MegaTTS3 on **Windows**, including:

- `pynini` build errors via `pip`
- Suggested `conda` workaround
- Version compatibility issues (e.g., `gradio`, `pydantic`)
- Directory layout for checkpoints
- Proposal to include Gradio-based WebUI

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## ✅ Environment

- OS: Windows 11
- Python: 3.10
- pip: latest
- Conda: yes

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## 🔧 Problems Encountered

### 1. `pynini` build fails via pip, now i tring the `conda install -c conda-forge pynini=2.1.5`

Start by reproducing the Windows 11 setup with Python 3.10, focusing on the reported pip failure for pynini and the listed dependency compatibility issues. Review the existing setup and deployment instructions, then verify that the documented installation, checkpoint layout, and proposed WebUI expectations work on Windows.

Written by the indexing model from the issue text.