* Studio: surface the real reason a model fails validation
validate_model caught every error and returned a blank "Invalid model" while
logging the actual cause. Selecting a GGUF model without a built llama-server,
for example, raises a deliberately actionable RuntimeError ("llama-server binary
not found - cannot load GGUF models. Run setup.sh ...") that the user never saw,
leaving them with an unexplained "Invalid model".
Surface RuntimeError and ValueError messages (path-redacted, and wrapped with the
existing "not supported yet" hint where it applies) in the 400 detail, matching
what the native-path branch already does. Any other exception type stays generic
so an unexpected internal error never leaks its details to the client.
* [pre-commit.ci] auto fixes from pre-commit.com hooks
for more information, see https://pre-commit.ci
* Test: accept positional args in the from_identifier mock
Make the mock robust to a future from_identifier signature that passes
positional arguments, per review feedback.
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Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
