common : fix -hf tag matching inside longer quant names (#31620)
* common : fix -hf tag matching inside longer quant names
":F16" picked a BF16 file when the repo had both, since "BF16"
contains "F16". The same applied to ":Q4_XS" vs "IQ4_XS". The tag
now has to start at a token boundary in the path.
Assisted-by: dsh:llama.cpp/ggml-org/GLM-5.3-Flash-GGUF (Mac Studio, M5 Ultra, 256GB)
* common : accept underscore as -hf tag boundary
Some repos separate the quant with an underscore, e.g.
stepfun-ai/Step-3.5-Flash-GGUF-Q4_K_S ships
step3p5_flash_Q4_K_S-00001-of-00012.gguf, which :Q4_K_S no longer
matched. Add _ to the token boundary and pin the tag and default
lookup cases.
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Co-authored-by: Pascal <admin@serveurperso.com>