Plugin API reference data endpoints

New read-only endpoints expose models, sceneries, AI providers, aspect ratios, and pricing so plugin developers can build full session configurators.

The Plugin Integration API now exposes the reference data plugin developers need to build session configurators on their merchant side. Five new endpoints — /models, /sceneries, /ai-models, /aspect-ratios, and /pricing — return the catalog of available mannequins, scenes, AI providers, aspect ratios, and per-job credit costs. The existing /presets endpoint has been extended to include quantity_guidelines, quality_guidelines, and gallery so the preset detail screen no longer needs to fall back to legacy endpoints.

All new endpoints are gated by a dedicated plugin.catalog:read scope, automatically granted to every active installation. The /ai-models response is filtered server-side by the account's subscription plan, so plugins always receive only the models the merchant is entitled to use. The OpenAPI 3.1 contract, example responses, and the per-endpoint caching policy are documented at /docs/plugin-api.