Consolidate the duplicate name-matching logic into ModelScanner:
find_matching_models is now the single core, using each scanner's own
file_extensions for suffix stripping. get_model_info_by_name gains
require_unique/base_model kwargs while legacy route behavior is kept
byte-identical. reconnect_lora passes the recipe base model as a guard
and distinguishes ambiguous, base-model-mismatched, and missing LoRAs
in its error messages.