[Change] Refine gguf path resolution/search to make sure it respects snapshot revisions

[dbotwinick]

resolve_gguf_path() now glob-searches the entire model cache and returns the first lexicographically-sorted match. In the HuggingFace cache this can include multiple snapshot revisions, so this can select an older (or otherwise unintended) GGUF file when several revisions are present. Consider limiting the search to a specific snapshot (e.g., the commit referenced by refs/main or by an optional revision parameter) and/or prefer the most recently-modified snapshot before picking the first shard.

Originally posted by @Copilot in #9 (comment)

[dbotwinick]

Deferred for now. It's a reasonable thing to do/consider, but there are many higher priority things to do and so far, I don't think anyone has ever noticed this -- users typically want the latest version rather than a snapshot revision.