fix: load official SenseVoice ONNX models

[LauraGPT]

Fixes #101.

Summary

• detect model_quant.onnx and pass quantize=True to funasr_onnx.SenseVoiceSmall
• keep custom non-quantized model.onnx directories working with quantize=False
• validate the required config, CMVN, tokenizer, and ONNX files before importing/loading the runtime
• document the exact two-repository ModelScope preparation flow in Chinese and English

The official iic/SenseVoiceSmall-onnx repository ships model_quant.onnx but does not include chn_jpn_yue_eng_ko_spectok.bpe.model, while the existing loader used the constructor default quantize=False. This made the documented SenseVoice path fail even after downloading the official ONNX repository.

Validation

• 59 passed with the locked project environment (uv sync --extra web)
• focused quantized, non-quantized, and missing-tokenizer regression tests
• Ruff check and format check on changed Python files
• Python compile check and git diff --check
• verified the actual funasr-onnx==0.4.1 wheel constructor supports quantize: bool = False
• verified both referenced ModelScope repositories are reachable