Clarify GPU quickstart PyTorch setup

[LauraGPT]

Summary

• document that CPU-only quickstarts can use default PyPI torch wheels
• tell GPU users to install PyTorch/torchaudio CUDA wheels from pytorch.org and verify torch.cuda.is_available() before using device="cuda"
• record the 2026-07-23 clean CPU/GPU venv quickstart evidence and the remaining CUDA visibility blocker

Tests

• python3 -m pytest tests/test_growth_plan_doc.py tests/test_check_funasr_website_static.py -q
• python3 scripts/check_funasr_website_static.py --timeout 20 --retries 1

[gemini-code-assist]

Caution

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