MCP tool: report the render-mode configuration for a Caravela
domain's entities — which ones use :live vs :rest, and whether
:rest entities opt into SSE realtime.
Lets an LLM host know which transport each entity uses before
suggesting code. Without this, a host asked "how do I add a form
to BookIndex" can't tell whether the entity is rendered through
LiveView's WebSocket or through caravela_svelte's Inertia-style
HTTP — and those need different client-side patterns.