[Feature]: support and eval H-Scale: Hessian-Guided Scale Refinement for NVFP4 Sub-Byte LLM Inference

### Feature Description

Though I think iMatrix has already done a large part of the work for Hessian part, let's evaluate it when we have some bandwidth.

### Motivation and Use Case

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### Alternatives Considered

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### Definition of Done

_No response_

### Additional Context

_No response_

No files, tests, entry points, or acceptance criteria are named. Start by locating the existing iMatrix Hessian-related implementation and the NVFP4 quantization and inference entry points, then determine how H-Scale should be evaluated and what results would constitute completion.

Written by the indexing model from the issue text.