Per-entity render state for the per-instance rendering tier
(server-spawned characters / creatures / equipped items). Holds:
- partGfxObjOverrides: Dictionary<int, ulong> — AnimPartChange swaps
(e.g. wielding a weapon replaces a hand-part's GfxObj).
- hiddenMask: ulong — HiddenParts bitmask. Bit i set hides part i.
- AnimationSequencer reference — N.4 doesn't touch the sequencer;
this just exposes it for the draw dispatcher.
Public API: HideParts / IsPartHidden / SetPartOverride /
TryGetPartOverride / ResolvePartGfxObj. Bounds-checked
(partIdx < 0 or >= 64 → IsPartHidden returns false).
Twelve tests covering the type, the AnimPartChange resolution helper,
and the HiddenParts bitmask edge cases (theories for 0b0/0b1/MSB/all-ones,
plus negative-index + out-of-range guards).
Consumed by Task 17's EntitySpawnAdapter (creates one per CreateObject)
and Task 22's WbDrawDispatcher (reads via per-part draw loop).
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>