[Feature] Add Qwen3.8-27B local-Hessian PTQ recipes

[realAsma]

What does this PR do?

Type of change: new feature

Adds a reusable NVFP4 W4A4 local-Hessian PTQ recipe and a checkpoint-specific recipe for Qwen/Qwen3.8-27B.

The checkpoint recipe reproduces the validated 5.5-bit NVFP4-max AutoQuantize assignment: NVFP4 W4A4 for MLP projections and lm_head, FP8 W8A8 for self-attention and large linear-attention projections, and no quantization for the vision tower, MTP layers, KV cache, or linear_attn.in_proj_a/b.

This PR is stacked on #2339.

Usage

cd examples/hf_ptq
python hf_ptq.py \
  --pyt_ckpt_path Qwen/Qwen3.8-27B \
  --recipe models/Qwen/Qwen3.8-27B/ptq/autoquant_nvfp4_max_5p5bits_local_hessian \
  --export_path <quantized_ckpt_path>

Local-Hessian calibration currently requires a single-rank run.

Testing

• pre-commit run --files <five changed paths>
• pytest tests/unit/recipe/test_loader.py tests/unit/recipe/test_recipe_docs.py -q -x — 321 passed
• Loaded and resolved both added recipes.
• Compared the Qwen recipe against the final checkpoint hf_quant_config.json; all 401 quantized modules matched the expected FP8/NVFP4 formats.

Before your PR is "Ready for review"

• Is this change backward compatible?: ✅
• If you copied code from any other sources or added a new PIP dependency, did you follow guidance in CONTRIBUTING.md: ✅
• Did you write any new necessary tests?: N/A — existing recipe discovery and documentation tests cover both additions.
• Did you update Changelog?: ✅
• Did you get Claude approval on this PR?: N/A

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