fix(model-artifacts): load single-file HF snapshots from the file, not the dir
The managed Hugging Face artifact materializer (#10825) always pointed
backends at the snapshot *directory*
(.artifacts/huggingface/<key>/snapshot). For a single-file model
reference such as huggingface://nomic-ai/nomic-embed-text-v1.5-GGUF/nomic-embed-text-v1.5.f16.gguf,
the GGUF lives *inside* that directory, so llama.cpp was handed a
directory and failed with "gguf_init_from_reader: failed to read magic".
This has kept the tests-aio job red on master since the feature merged
(the embeddings e2e tests could not load text-embedding-ada-002).
Record the single file of a one-file snapshot as Resolved.PrimaryFile and
have ModelFileName() resolve to snapshot/<PrimaryFile> when it is set.
Multi-file snapshots (e.g. transformers repos consumed as a directory)
keep pointing at the snapshot directory. PrimaryFile is derived from the
resolved contents and is deliberately excluded from the artifact cache
key. estimateModelSizeBytes now derives the snapshot directory from the
cache key instead of ModelFileName(), so its manifest lookup is unaffected
by the file-vs-directory resolution.
Assisted-by: Claude:opus-4.8 [Claude Code]
Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
Co-authored-by: Ettore Di Giacinto <mudler@localai.io>
