OpenAPI contracts

Sources: internal/controller/openapi.client.json and openapi.admin.json. Tests: TestOpenAPIRoutesSync, TestPlaneSpecsValid, TestOpenAPIForbiddenNames / TestOpenAPIFieldTables. Handler JSON changes must update the owning plane file.

yarn docs:build copies those files as openapi.client.json (client + store) and openapi.admin.json (admin + CI). It no longer slices by /store/ or CI paths. User downloads and Scalar new windows: API reference. Do not hand-copy field tables.