_normalize_method_name canonicalizes dashes to underscores for _OVERRIDES
lookup, but vLLM's QUANTIZATION_METHODS keeps historical spellings
('compressed-tensors'), so both --quantization compressed-tensors and
checkpoint auto-detection raised 'Unknown quantization method'. Resolve
the normalized name back to the registry spelling, and fall back to
from_config for registry configs whose __init__ does not take the
serialized schema (compressed-tensors config_groups/format/ignore).