Rig a 3D model: generate a skeleton and skin weights for an existing GLB so it can be animated. Accepts a URL or base64-encoded GLB in `model`. Synchronous: the call blocks while the rig is generated, then returns a downloadable `model_url` for the rigged GLB. rig_type selects the skeleton prior — general (default, any asset), humanoid (anime-style characters), game (classic game-character rigs), or the pinned humanoid templates for two-armed, two-legged characters: humanoid_template (standard 22-joint skeleton with named joints, required for animating from the preset library) and humanoid_template_hands (52 joints, five fingers per hand). joint_naming relabels the identified joints to a convention — smpl (default), mixamo, humanik, unreal, godot, rigify, or vroid — without changing the skeleton. Credits are charged only on success. Rigging is non-destructive to geometry but replaces any prior skeleton, so animations made against an old rig no longer apply. Requires an API key (user scope).