Renders real PhiaUI components dynamically for the design canvas.

Attempts to call the actual component function with the node's attrs and slots. Falls back gracefully to {:error, reason} on any failure so the editor can show a placeholder instead.

Slot construction

inner_block text content is wrapped in a proper Phoenix slot struct so that render_slot(@inner_block) works inside the target component. Named slots are not supported yet (they require compile-time HEEx).