Returns the authoritative routable set for the caller: the auto-routable catalog (base
restricted to the organization's callable models and the caller's effective model access rule —
the organization rule with the caller's live team's exceptions, like the providers API's
caller-scoped fetches) filtered by the allowlist that applies to the caller — the caller's
team's rule when the caller has a live team with a rule, else the organization's rule; without
any rule the catalog is returned unchanged. The caller's team is resolved from the identity on
the auth token. API keys resolve to their owning subject; service accounts have no team
memberships and always get the organization rule.

Gated on PROVIDERS/READ rather than AUTO_MODEL_ROUTING because the proxy calls this with the
caller's key — the same trust tier as the providers fetch that already carries model-access
enforcement — so every role that can use the LLM endpoints (Kimchi Workspace, Code Reviewer
Proxy, providers-read-scoped PATs) can resolve its routable set without role changes.