fix(anim): the clip now drives the body — two causes, both measured

The body stood in an A-pose while the log said the clip was playing. Two
independent defects, found by querying the imported asset instead of guessing:

1. PlayAnimation needs the component in AnimationSingleNode with a live
   single-node instance. The body is hidden at construction and only unhidden by
   the camera toggle, so the first call could land before the component was ready,
   and the Wanted == PlayingAnimation guard then returned forever. UpdateBodyAnimation
   now sets the mode, calls SetAnimation + Play, and re-asserts while the instance
   is missing.
2. The arms-down offsets lived only in the clip keys. The exporter writes clip data
   relative to the rest pose, so they arrived as a ±20 degree swing around an
   A-posed bind - which is exactly what the pose probe measured. apply_base_pose now
   bakes them into the rest pose before any clip is authored, the same trick
   mpfb_character_export.py --pose idle uses. The table is applied with inverted
   signs: as written, the FBX axis mapping produced arms raised in a V.

Shot 6 confirms it: the arms hang at the sides. Still open and recorded - the idle
pose reads awkwardly (arms forward, hands splayed) and the walk clip has no shot in
motion; both are marked in TODO.md and Screenshots/README.md.

Instrumentation removed; the diagnostics that remain are behind
gigline.SetupLogs.

TODO.md

@@ -17,7 +17,7 @@ Actionable task list for this project. This file is the single, central place fo
 - [x] Import character into Unreal; validate skeleton, scale, and materials. Done: `/Game/Test/Character` — `SkeletalMesh` (138 bones), `Skeleton`, warm `M_Character_Export` material with baked `T_Character_Diffuse`.
 - [x] Promote the character asset into a reusable NPC prefab (visible body, collision capsule, idle pose) ready for pedestrians (`0.5.0`) once the third-person body lands. Done 2026-11-07: `AGigLineNPCPerson` (see the 0.1.0 Character-development item); `0.5.0` reuses it as the pedestrian base.
 - [x] Create basic idle/walk animation set. Done 2026-11-09: `Tools/character_anim_build.py` authors `GigLine_Idle` (60 f) and `GigLine_Walk` (30 f) at 30 fps from parametric cycles, and `Tools/ue_character_anim_import.py` imports them. Both AnimSequences verified in `/Game/Test/Character`: Idle 1.967 s, Walk 0.967 s. Limb axes were **measured** on the rig, not assumed — the probe rotated `upperleg01.L` 0.5 rad per axis and read `foot.L`, which showed X is the fore/aft swing (Y twists, Z abducts).
-- [A] Verify animation plays correctly on the imported rig. **Playback is broken and now measurable**: the pawn's mesh is bound, both clips resolve, and the run logs `GigLine: playing body clip Character_AnimHuman_rig_GigLine_Idle`, but shot 5 still renders the body in bind pose (arms out). So `PlayAnimation` is called and the pose is not applied — next step is to check whether the imported clip carries bone curves at all (the FBX bake may be sampling only keyed bones) or whether the component needs `SetAnimationMode(AnimationSingleNode)` before `SetAnimation`/`Play`.
+- [~] Verify animation plays correctly on the imported rig. **Fixed 2026-11-09**: the clip now drives the body — shot 6 shows the arms hanging at the sides instead of an A-pose. Two causes, both proven by measurement rather than guessed: (1) `PlayAnimation` needs the component in `AnimationSingleNode` with a live single-node instance, and the body is hidden at construction, so the first call could land before the component was ready and never retry; the code now sets the mode, calls `SetAnimation` + `Play`, and re-asserts while the instance is missing. (2) the arms-down offsets were carried only in the clip keys, which the exporter writes relative to the rest pose — so they arrived as a ±20° swing around an A-posed bind; they are now baked into the rest pose before the clips are authored (`apply_base_pose`). **Still open:** the idle pose reads awkwardly (arms hang forward, hands splay) because the base is applied with inverted signs to compensate for the FBX axis flip, and the walk clip has never been captured in motion. Earlier evidence: the pawn's mesh is bound, both clips resolve, and the run logs `GigLine: playing body clip Character_AnimHuman_rig_GigLine_Idle`, but shot 5 still renders the body in bind pose (arms out). So `PlayAnimation` is called and the pose is not applied — next step is to check whether the imported clip carries bone curves at all (the FBX bake may be sampling only keyed bones) or whether the component needs `SetAnimationMode(AnimationSingleNode)` before `SetAnimation`/`Play`.
 
 ### Camera and controls