feat(D-01/E): quickwins — debug toggle, HumanChairHelper move, collar equip

Q1: Remove F9 debug toggle from GltfAnimationApplier + delete dead
    GltfRenderLayer + remove keybind registration

Q2: Move HumanChairHelper from state/ to util/ — pure utility with
    no state dependency. 7 import updates.

Q3: Wire NECK collar equip flow in DataDrivenBondageItem:
    - Target must be tied up (V1 rule preserved)
    - Distance + line-of-sight validation
    - Owner added to NBT before equip via CollarHelper.addOwner()
    - V2EquipmentHelper handles conflict resolution
    - ModSounds.COLLAR_PUT played on success
    - OwnershipComponent.onEquipped registers in CollarRegistry

src/main/java/com/tiedup/remake/client/gltf/GltfAnimationApplier.java

@@ -13,8 +13,6 @@ import java.util.Set;
 import java.util.TreeSet;
 import java.util.UUID;
 import java.util.concurrent.ConcurrentHashMap;
-import net.minecraft.client.Minecraft;
-import net.minecraft.client.player.AbstractClientPlayer;
 import net.minecraft.resources.ResourceLocation;
 import net.minecraft.world.entity.LivingEntity;
 import net.minecraftforge.api.distmarker.Dist;
@@ -433,52 +431,6 @@ public final class GltfAnimationApplier {
         ContextAnimationFactory.clearCache();
     }
 
-    // LEGACY F9 DEBUG TOGGLE
-
-    private static boolean debugEnabled = false;
-
-    /**
-     * Toggle debug mode via F9 key.
-     * When enabled, applies handcuffs V2 animation (rightArm + leftArm) to the local player
-     * using STAND_IDLE context. When disabled, clears all V2 animation.
-     */
-    public static void toggle() {
-        debugEnabled = !debugEnabled;
-        LOGGER.info(
-            "[GltfPipeline] Debug toggle: {}",
-            debugEnabled ? "ON" : "OFF"
-        );
-
-        AbstractClientPlayer player = Minecraft.getInstance().player;
-        if (player == null) return;
-
-        if (debugEnabled) {
-            ResourceLocation modelLoc = ResourceLocation.fromNamespaceAndPath(
-                "tiedup",
-                "models/gltf/v2/handcuffs/cuffs_prototype.glb"
-            );
-            Set<String> armParts = Set.of("rightArm", "leftArm");
-            RegionBoneMapper.BoneOwnership debugOwnership =
-                new RegionBoneMapper.BoneOwnership(armParts, Set.of());
-            applyV2Animation(
-                player,
-                modelLoc,
-                null,
-                AnimationContext.STAND_IDLE,
-                debugOwnership
-            );
-        } else {
-            clearV2Animation(player);
-        }
-    }
-
-    /**
-     * Whether F9 debug mode is currently enabled.
-     */
-    public static boolean isEnabled() {
-        return debugEnabled;
-    }
-
     // INTERNAL
 
     /**