Bondage test items : placeholder assets for Phase 3 pipeline validation

Adds minimum viable assets to exercise the Phase 3 anim pipeline
in-game :

- 5 placeholder anim JSON files in assets/tiedup/animmodels/animations/
  (identity keyframes matching context_stand_idle template) :
  armbinder_idle, armbinder_walk, armbinder_struggle,
  armbinder_equip_oneshot, classic_collar_idle
- armbinder.json enriched with 'animations' block binding IDLE + WALK
  + WALK_BOUND + STRUGGLE_BOUND living_motions + on_equip oneshot
- classic_collar.json enriched with IDLE binding for multi-item
  composition test

Purpose : validate end-to-end that the data-driven pipeline fires
correctly (rebuild, motion switch, oneshot sound, rehydrate) via F6
debug overlay. Visual pose does not change (identity anims) — body
keyframe authoring remains blocked on Blender artist assets.

Runtime note : the placeholder JSONs lack the EF 'constructor' block,
so readResourcepackAnimation does not register them in
AnimationManager.animationByName. resolveWithFallback will return
EMPTY_ANIMATION with a dedup WARN per missing ID — this exercises
the binding resolution path without needing a real StaticAnimation
(the map livingAnimations still receives the accessor, F6 overlay
still reports bindings:N). Real registration will land when either
InstantiateInvoker.getArmature() is implemented (Phase 2 armature
registry) or a dedicated AnimationRegistryEvent handler is added.

Gameday verification steps documented in docs/plans/rig/GAMEDAY_CHECKLIST.md
(gitignored, local only).

src/main/resources/assets/tiedup/animmodels/animations/armbinder_walk.json

@@ -0,0 +1,15 @@
+{
+  "_comment": "PLACEHOLDER gameday — identity walk pour armbinder (2 keyframes Root, 1s loop). Le but est de tester le switch de motion IDLE→WALK au runtime : F6 overlay doit afficher 'motion: WALK' quand le joueur bouge. Identité visuelle pour l'instant, remplacement Blender-authored (démarche contrainte, épaules raides) quand dispo.",
+  "_comment_registration": "Même statut que armbinder_idle.json : pas de bloc 'constructor' => resolveWithFallback retourne EMPTY_ANIMATION. Valide le switch de motion côté binding map sans besoin d'un StaticAnimation réel.",
+  "format": "ATTRIBUTES",
+  "animation": [
+    {
+      "name": "Root",
+      "time": [0.0, 1.0],
+      "transform": [
+        { "loc": [0.0, 0.0, 0.0], "rot": [1.0, 0.0, 0.0, 0.0], "sca": [1.0, 1.0, 1.0] },
+        { "loc": [0.0, 0.0, 0.0], "rot": [1.0, 0.0, 0.0, 0.0], "sca": [1.0, 1.0, 1.0] }
+      ]
+    }
+  ]
+}