animation asset type

• data.zanim — the engine-native binary clip payload (bincode AnimAsset): bone-named tracks, duration, channels. This is the asset's primary; consumers reference the .animation asset's guid, never this inner file. Parallel to how .mesh carries data.zmsh.
• humanoid.profile (optional) — the editable retarget holder: the clip's source-rig role↔bone map, so any humanoid rig can consume the clip. Written by the retarget setup (animation.onCreate path), inspectable and hot-reloaded.

Clips are produced by the model importers (model, model_animation), which decode embedded animation tracks and call asset.create("animation", name, { bytes }). Bare .anim files are the legacy shape; the .animation composite supersedes them (existing .anim guids are inherited by their migrated .animation asset so references keep resolving).