Harden the max-instances guard against the concurrent case: request_model now
resolves a GGUF text model to its absolute .gguf path (via _resolve_local_gguf)
before building model_key, so every name form — bare id, basename.gguf, full path,
or alias (e.g. "lisa") — collapses to ONE model_key. That gives a single
self.models entry and a single instance pool, so two simultaneous first-requests
under different forms converge on the same pool and the second queues instead of
loading a second instance. Complements the earlier already-loaded fuzzy match
(which only covered the sequential case).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>