feat(typescript-client): replace Promise<any> with concrete generated types

[solidprinciples]

Summary

The directive, mental model, and document methods on HindsightClient were all typed as Promise<any>. The generated types in types.gen.ts already had correct response shapes - they just weren't being used.

• Replace Promise<any> with concrete types across 13 methods
• Re-export all new types from the package entry point
• getMentalModelHistory typed as Promise<unknown> - the OpenAPI spec has no defined response schema for this endpoint

No runtime behavior changes. Types only.

Changes

Method	Before	After
createDirective	Promise<any>	Promise<DirectiveResponse>
listDirectives	Promise<any>	Promise<DirectiveListResponse>
getDirective	Promise<any>	Promise<DirectiveResponse>
updateDirective	Promise<any>	Promise<DirectiveResponse>
createMentalModel	Promise<any>	Promise<CreateMentalModelResponse>
listMentalModels	Promise<any>	Promise<MentalModelListResponse>
getMentalModel	Promise<any>	Promise<MentalModelResponse>
refreshMentalModel	Promise<any>	Promise<AsyncOperationSubmitResponse>
updateMentalModel	Promise<any>	Promise<MentalModelResponse>
getMentalModelHistory	Promise<any>	Promise<unknown>
getDocument	Promise<any | null>	Promise<DocumentResponse | null>
listDocuments	Promise<any>	Promise<ListDocumentsResponse>
updateDocument	Promise<any>	Promise<UpdateDocumentResponse>

Test plan

• tsc --noEmit passes clean
• All 32 existing tests pass

[solidprinciples]

@nicoloboschi - noticed the package.json links to your fork/repo (?) - worthwhile to update it in this PR?