fix: runtime bugs in recipe validation, autoround, and awq

[soyr-redhat]

The goal of this pr is to just fix a couple of bugs that arise at runtime

1. truncated error message in AWQ recipe validation
the error message at recipe/recipe.py:225 ends mid-sentence with "AWQ must be run with " and never finishes. THere's also a typo, "modifer" -> "modifier"

2. duplicate _unwrapper_quantized_layer in AutoRoundModifier
identical method defined at lines 394 and 435 of autoround/base.py. the second silently overwrites the first. I just simply removed the duplicate.

3. division by zero in AWQ _log_error_metrics
if _error_metrics is empty (e.g. all mappings skipped), sum(reductions) / len(reductions) raises ZeroDivisionError and min()/max() raise ValueError on empty sequence. added early return guard. This was mitigated by doing an early check for if not _error_metrics ahead of time.

no new tests should be required...these are fixes to existing error paths and dead code removal.

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[mergify]

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[gemini-code-assist]

Code Review

This pull request removes the unused _unwrapper_quantized_layer method from the AutoRound modifier, adds a guard clause in the AWQ modifier to safely handle empty error metrics, and fixes a typo while completing an error message in the recipe validation logic. The reviewer suggested improving the error message in recipe.py by printing only the class names of the modifiers instead of dumping their full Pydantic string representations, which can be overly verbose.

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