Release v5.0.0

Added

• TierModelAssignment, which infers the tier ladder from a provider's own catalog: the words vendors use at the small and large ends of their range, with the highest version winning inside a rung.

Changed

• A model tier that no operator mapped is now resolved from the models the provider actually published, rather than from a built-in per-vendor table of model names. A tier can no longer resolve to a model a provider does not serve.
• TierModelResolution.Resolve takes the provider's available models in place of its AIProviderType. An explicit mapping still wins, tier by tier.

Removed

• TierModelDefaults, the built-in table of per-vendor model names. It had already drifted from what the vendors serve - it named models that had been renamed, and one that never existed - and a tier pointing at a name the vendor does not serve fails silently, landing on whatever the harness falls back to.