fix(llm): answer a catalog route's models from pi-ai's own registry

Clicking "fetch available models" on a built-in provider went to the
network. That is the wrong source: pi-ai's registry is the authoritative
list for its own providers, and it carries the context windows and output
caps a `GET /models` listing does not disclose. Asking api.deepseek.com
what DeepSeek serves is both slower and worse, and against an endpoint
that answers a different shape it failed outright.

Interrogation is still keyed by settings namespace — the provider being
added has no route — but the request may now name the route it is
editing. An adapter that already describes that route answers from what
it knows, needs no endpoint at all, and never touches the network; only a
route the catalog does not describe reaches the wire, and one naming no
endpoint is told to set one or enter its models by hand.

`ConfigurableProviderView` gained `supportsDiscovery` so a surface offers
the action where a namespace can answer instead of hardcoding an adapter
family.

Three narrower corrections ride along. Discovery no longer claims Azure
or Codex: Azure authenticates with an `api-key` header and an
`api-version` query despite its OpenAI lineage, and Codex uses OAuth, so
both reported an authentication failure as a provider with no models.
Cancellation during the body read escaped as the raw abort reason rather
than a coded ABORTED. And the schema comment claiming the probe key is
never logged overstated it: the host neither stores nor returns it, but
it rides the client's outgoing envelope like every other secret-bearing
payload, and redacting that tap is a configuration-plane-wide change.

packages/llm/llm/README.md

@@ -26,7 +26,7 @@ An adapter registry plus a single streaming call surface, interceptable via a wa
 
 `LlmService` preserves errors from final adapter selection, synchronous dispatch, iterator construction, and iteration, and binds their provenance to the exact stream handle returned for that model call. `isLlmAdapterFailure(stream, value)` reports only errors from that call's final adapter boundary; `llmFailureOf(stream, value)` returns the adjacent immutable `LlmFailure`; `llmRetryPolicyOf(stream)` returns the immutable policy of the exact registration selected at that boundary, even if the route is later disposed or replaced. A call that never reaches a final adapter has no serving policy. Nested model calls, `llm/stream` middleware, and downstream consumer failures remain unclassified for the outer call. Classification never replaces or mutates the adapter's original coded `Error`.
 
-Interrogating an endpoint is configuration-time work over a *draft*, which is why it is keyed by settings namespace rather than by provider route: the provider a surface is adding does not exist yet, so there is no route to name. The request carries the endpoint, the protocol, and a credential the harness uses for that one interrogation and never stores — nothing here reads or writes settings or credentials, and the reply is candidate metadata a surface may offer for adoption, never a registered catalog. `LlmDiscoveredModel` makes every field but `id` optional because most provider listings disclose an id and nothing else; a surface adopting one still owes the capacities its adapter requires. Duplicate and unusable ids are dropped, an unserved namespace fails with `NO_DISCOVERY`, and an empty namespace or endpoint fails with `INVALID_DISCOVERY`.
+Interrogating an endpoint is configuration-time work over a *draft*, which is why it is keyed by settings namespace rather than by provider route: the provider a surface is adding does not exist yet, so there is no route to name. The request may still *name* a route it is editing, and an adapter that already describes that route should answer from its own knowledge — better metadata, no network call — which is why `baseURL` is optional and one of the two is required. The request otherwise carries the endpoint, the protocol, and a credential the harness uses for that one interrogation and never stores — nothing here reads or writes settings or credentials, and the reply is candidate metadata a surface may offer for adoption, never a registered catalog. `LlmDiscoveredModel` makes every field but `id` optional because most provider listings disclose an id and nothing else; a surface adopting one still owes the capacities its adapter requires. Duplicate and unusable ids are dropped, an unserved namespace fails with `NO_DISCOVERY`, and a request naming neither a route nor an endpoint fails with `INVALID_DISCOVERY`.
 
 Provider and model metadata is a discovery surface, not a routing whitelist. `registerAdapter()` still owns provider exclusivity and captures the adapter's retry policy for each route, while an adapter may accept model ids absent from `listModels()`; consumers must not reject a request because its model is unlisted. Returned selector metadata is detached and invalid or duplicate adapter entries fail with `INVALID_ADAPTER` or `INVALID_CATALOG`.