Push URL host knowledge from `Endpoint` (route layer) up to `model.baseURL`
(provider helper layer). The route just composes a path onto whatever
host the model already carries.
Endpoint:
- `Endpoint<Body>` shrinks to `{ path }`. No more `default`, `baseURL`,
or `required` fallback fields.
- `Endpoint.path(value)` replaces the old `Endpoint.baseURL({...})` factory.
- `Endpoint.render()` is now sync — `${model.baseURL}${path}` plus query
params. No fallback chain, no Effect wrapper.
ModelRef:
- `ModelRef.baseURL: Schema.String` (was optional). Every materialized
model carries a host.
- `RouteModelInput.baseURL?: string` stays optional so route defaults
can supply a canonical URL; routes without a default tighten it.
Provider helpers:
- Each protocol exports a `DEFAULT_BASE_URL` constant and bakes it into
`route.defaults.baseURL`. Provider helpers don't need to set baseURL.
- Azure uses a new `AtLeastOne<T>` helper from `auth-options.ts` to
require either `resourceName` or `baseURL` at the type level.
- Bedrock provider computes baseURL from `region` at construction time.
- OpenAI-compatible profiles now have required (not optional) `baseURL`
in their type — all 9 already supplied one.
- The `defaultBaseURL: string | false` knob on protocol endpoint
factories is gone.
Effects:
- Forgetting baseURL is now caught at compile time (TS) or model
construction time (modelWithDefaults runtime check), not request time.
- `Endpoint.render` no longer needs Effect wrapping in the transport
hot path.
Group Protocol fields by direction: `body: { schema, from }` for the
request side and `stream: { event, initial, step, terminal, onHalt }`
for the response side. Rename `Protocol.define`→`Protocol.make` and
`Protocol.jsonChunk`→`Protocol.jsonEvent` to match the rest of the
codebase. Type aliases follow: `*Payload`→`*Body`, `*Chunk`→`*Event`.
Kit Langton