Body step 2.1: climbing, mantling, crawling, legs, playground, 144 Hz

- Step rule + lower-body collider: no walking onto tables, steps <= 0.35 m
- Structural hand strength: two-hand mantle/pull-up works, one hand can't
- Arms aim from the physical shoulder horizontally, keep True Body pose vertically
- Crawl pose, crawl carry, 35 deg slope limit, ground feed-forward ignores
  play-space corrections (fixes a runaway feedback loop)
- Grab static world (climbing), procedural visual legs
- Playground sandbox; menu strength slider, spectator (old drag) and turn toggles
- Physics 144 Hz with interpolation; legacy chase-body spikes pin 90 Hz
- RagdollSpike: 27 phases incl. mantle, pull-up, crawl, ledge drop, ramps

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()
     {
+        // Legacy chase bodies (PhysicsHands/Torso/Arms) were tuned at 90 Hz; the project runs 144 Hz
+        // since body step 2, so this regression pins their design rate.
+        Engine.PhysicsTicksPerSecond = 90;
         // 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);