feat(ui-models)!: single-key hand-written provider editors with derived credential references

The Models page drops the generic schema renderer and the visible
environment-variable field: each editor is a curated per-family card whose
primary input is one write-only API key stored under a derived
<ROUTE>_API_KEY reference (recorded as apiKeyEnv in the pi-ai profile), an
unkeyed whole-section provider opens as its setup card, and the collapsed
customized-settings fold carries baseURL/reasoningEffort (deepseek) or
reasoning (pi-ai). dsh-client-schema-form reduces to the schema/draft model
layer (no React).

packages/client/schema-form/src/index.ts

@@ -1,16 +1,12 @@
 /**
- * Schema-driven React form renderer for settings sections. `SchemaForm`
- * rehydrates the wire's serialized schemastery envelope and edits a draft
- * user section against it; the model helpers expose the same introspection
- * and immutable path editing for page-level composition.
+ * Schema/draft model layer for settings editors: rehydrate the wire's
+ * serialized schemastery envelope, resolve nodes by settings path, validate
+ * drafts, and edit them immutably by path. Editors render their own controls
+ * (the Models page hand-writes its layout) on top of these helpers.
  * @module @deepseek-ai/dsh-client-schema-form
  */
 
-export { SchemaForm } from './SchemaForm.tsx'
-export type {
-  SchemaFieldContext, SchemaFormLabels, SchemaFormProps, SchemaFormSecret,
-} from './SchemaForm.tsx'
 export {
-  deletePath, getPath, hasPath, nodeAtPath, nodeKind, rehydrateSchema, setPath, unionChoices, validateDraft,
+  deletePath, getPath, hasPath, nodeAtPath, rehydrateSchema, setPath, validateDraft,
 } from './model.ts'
-export type { NodeKind, SchemaNode } from './model.ts'
+export type { SchemaNode } from './model.ts'