Body step 1: one-time T-pose calibration (prefs.json, forced gate) + True Body solver + shared ArmSolver

- BodyProfile (Winter anthropometry, T-pose: arm = (span - shoulder width)/2 - 1.5 cm) and
  Prefs (gitignored prefs.json next to the executable / project folder in editor builds)
- Calibration node: loads prefs, else head-locked prompt + jitter-proof TPoseDetector; body
  systems wait for BodyProfile.Current; Recalibrate() in group "calibration"; recal rebuilds arms
- ArmSolver: PhysicsArms' elbow solve extracted (behaviour-identical) + min reach |U-F| fix
- TrueBody: derived real-body pose (neck, chest yaw + crouch lean at neck pivot, lagging pelvis,
  moving shoulder girdle with scapulohumeral shrug, arms) + debug skeleton
- PhysicsArms/PhysicsTorso/BodyRig now profile-driven (arm length no longer from head height)
- TrueBodySpike PASS x3; all spikes PASS x3 (arm spike thresholds re-based for correct 0.57 m arms;
  CollapseSpike uses a fixed standing profile)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

scripts/CollapseSpike.cs

@@ -58,6 +58,9 @@ public partial class CollapseSpike : Node3D
 
     public override void _Ready()
     {
+        // A real profile is measured standing once (T-pose) and does not shrink when seated:
+        // every scenario, seated or not, uses the same standing 1.65 m-eye profile.
+        BodyProfile.Current = BodyProfile.Estimate(1.65f);
         // Seated head 1.01 m (the playtest calibration); chest center z = head z + 0.12.
         // Table front edge is z = -0.2, chest half-depth 0.065: overlap starts at head z < -0.255.
         Add("standing, no table overlap, anvil", new(0.2f, 1.65f, 0.3f), 6f, anvil: true, table: true);