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/PropGrabber.cs

@@ -11,6 +11,8 @@ public partial class PropGrabber : Node
     private const float BreakTime = 0.25f;
     private const float BreakDistanceBoth = 0.4f;
     private const float GripRipDistance = 0.8f;
+    private const float WorldGrabRadius = 0.05f;   // palm sphere for grabbing static world (ledges, bars, holds)
+    public const string NoGrabGroup = "no_grab";   // static bodies that can't be grabbed (the floor)
 
     private static PropGrabber _instance;
 
@@ -18,7 +20,7 @@ public partial class PropGrabber : Node
     private XRController3D _right;
     private PhysicsArms _arms;
 
-    private readonly RigidBody3D[] _held = new RigidBody3D[2];
+    private readonly PhysicsBody3D[] _held = new PhysicsBody3D[2];  // a prop, or static world (climbing)
     private readonly ConeTwistJoint3D[] _joints = new ConeTwistJoint3D[2];
     private readonly Vector3[] _localAnchor = new Vector3[2];
     private readonly uint[] _grabSeq = new uint[2];
@@ -59,7 +61,7 @@ public partial class PropGrabber : Node
 
         if (grip && !_gripPrev[hand] && _held[hand] == null)
         {
-            RigidBody3D prop = FindProp(controller, hand);
+            PhysicsBody3D prop = FindProp(controller, hand);
             RigidBody3D handBody = PhysicsHands.GetBody(controller);
             if (prop != null && handBody != null)
             {
@@ -68,26 +70,27 @@ public partial class PropGrabber : Node
                 Vector3 pivot = PalmPoint(handBody, hand);
                 _joints[hand] = MakeWeld(handBody, prop, pivot, RigidWeldBias);
                 _localAnchor[hand] = prop.GlobalTransform.AffineInverse() * pivot;
-                _arms?.SetHeld(hand, prop);
+                _arms?.SetHeld(hand, prop as RigidBody3D);
                 PlayerRig.SetHeld(controller, prop);
-                GD.Print($"PropGrabber: grabbed '{prop.Name}' ({prop.Mass:0.###} kg, {(hand == 0 ? "left" : "right")}{(_held[other] == prop ? ", two-handed" : "")})");
+                string what = prop is RigidBody3D rb ? $"{rb.Mass:0.###} kg" : "static world";
+                GD.Print($"PropGrabber: grabbed '{prop.Name}' ({what}, {(hand == 0 ? "left" : "right")}{(_held[other] == prop ? ", two-handed" : "")})");
             }
         }
 
         if (!grip && _held[hand] != null)
         {
-            RigidBody3D prop = _held[hand];
+            PhysicsBody3D prop = _held[hand];
             _held[hand] = null;
             DestroyJoint(hand);
-            if (IsInstanceValid(prop))
-                GD.Print($"PropGrabber: released '{prop.Name}' at {prop.LinearVelocity.Length():F2} m/s");
+            if (prop is RigidBody3D released && IsInstanceValid(released))
+                GD.Print($"PropGrabber: released '{released.Name}' at {released.LinearVelocity.Length():F2} m/s");
         }
         _gripPrev[hand] = grip;
     }
 
     private void HoldUpdate(XRController3D controller, int hand, float delta)
     {
-        RigidBody3D body = _held[hand];
+        PhysicsBody3D body = _held[hand];
         if (body == null)
             return;
         if (!IsInstanceValid(body))
@@ -148,7 +151,7 @@ public partial class PropGrabber : Node
         }
     }
 
-    private int PrimaryHand(RigidBody3D body)
+    private int PrimaryHand(PhysicsBody3D body)
     {
         int primary = -1;
         for (int hand = 0; hand < 2; hand++)
@@ -159,7 +162,7 @@ public partial class PropGrabber : Node
         return primary;
     }
 
-    private ConeTwistJoint3D MakeWeld(RigidBody3D handBody, RigidBody3D prop, Vector3 pivot, float bias)
+    private ConeTwistJoint3D MakeWeld(RigidBody3D handBody, PhysicsBody3D prop, Vector3 pivot, float bias)
     {
         ConeTwistJoint3D weld = new()
         {
@@ -175,7 +178,7 @@ public partial class PropGrabber : Node
         return weld;
     }
 
-    private void BreakGrip(int hand, RigidBody3D body, string reason)
+    private void BreakGrip(int hand, PhysicsBody3D body, string reason)
     {
         if (_held[hand] != body)
             return;
@@ -199,7 +202,7 @@ public partial class PropGrabber : Node
 
     private static float PalmOffset(int hand) => hand == 0 ? PalmGrabOffset : -PalmGrabOffset;
 
-    private RigidBody3D FindProp(XRController3D controller, int hand)
+    private PhysicsBody3D FindProp(XRController3D controller, int hand)
     {
         RigidBody3D handBody = PhysicsHands.GetBody(controller);
         if (handBody == null)
@@ -208,7 +211,27 @@ public partial class PropGrabber : Node
         RigidBody3D nearest = NearestProp(palm, GrabRadius);
         if (nearest != null)
             return nearest;
-        return NearestProp(handBody.GlobalPosition, CenterGrabRadius);
+        nearest = NearestProp(handBody.GlobalPosition, CenterGrabRadius);
+        if (nearest != null)
+            return nearest;
+        return WorldUnderPalm(palm, handBody.GetWorld3D());
+    }
+
+    // Climbing: any static body touching the palm (except the "no_grab" group) can be held.
+    private static StaticBody3D WorldUnderPalm(Vector3 palm, World3D world)
+    {
+        PhysicsShapeQueryParameters3D query = new()
+        {
+            Shape = new SphereShape3D { Radius = WorldGrabRadius },
+            Transform = new Transform3D(Basis.Identity, palm),
+            CollisionMask = 1,
+        };
+        foreach (Godot.Collections.Dictionary hit in world.DirectSpaceState.IntersectShape(query, 8))
+        {
+            if (hit["collider"].AsGodotObject() is StaticBody3D body && !body.IsInGroup(NoGrabGroup))
+                return body;
+        }
+        return null;
     }
 
     private RigidBody3D NearestProp(Vector3 point, float radius)