Implement collision bodies, physics events, and hit reactions for StickmanRig

- Added a new specification for collision bodies, detailing the implementation requirements and corrections needed in the StickmanRig, PropBlock, and SandboxStage scripts.
- Created a comprehensive test suite for collision bodies, including tests for proxy geometry, physics alignment, reaction handling, ghost collision, and stage contact routing.
- Ensured that the collision system correctly handles ragdoll transitions and maintains the integrity of existing event rules.
- Introduced new methods in StickmanRig for managing collision bodies and applying reactions based on impact direction and speed.
- Updated PropBlock to emit signals for collisions and separations, preserving the order of events for stickman and prop interactions.

scripts/prop_block.gd

@@ -33,6 +33,7 @@ const CIRCLE_SEGMENTS: int = 48
 const DEFAULT_FILL_COLOR := Color(0.55, 0.35, 0.15, 1.0)
 const DEFAULT_OUTLINE_COLOR := Color(0.15, 0.08, 0.02, 1.0)
 const DEFAULT_OUTLINE_WIDTH: float = 2.0
+const MAX_CONTACTS_REPORTED := 32
 
 # ---------------------------------------------------------------------------
 # Exported properties
@@ -94,7 +95,8 @@ var _circle_shape: CircleShape2D
 
 ## Emitted when this prop's body makes contact with another physics body.
 ## `other` is the body that entered contact (Phase 4 trigger source).
-signal collided(other: Node)
+signal collided(other: Node, contact_normal: Vector2, contact_position: Vector2)
+signal separated(other: Node)
 
 # ---------------------------------------------------------------------------
 # Lifecycle
@@ -106,13 +108,34 @@ func _ready() -> void:
 	_apply_style()
 	# Enable contact reporting so the body_entered signal fires (Phase 4).
 	contact_monitor = true
-	max_contacts_reported = 8
+	max_contacts_reported = MAX_CONTACTS_REPORTED
+	continuous_cd = RigidBody2D.CCD_MODE_CAST_SHAPE
 	if not body_entered.is_connected(_on_body_entered):
 		body_entered.connect(_on_body_entered)
+	if not body_exited.is_connected(_on_body_exited):
+		body_exited.connect(_on_body_exited)
 
 
 func _on_body_entered(body: Node) -> void:
-	collided.emit(body)
+	var center: Vector2 = (body as Node2D).global_position if body is Node2D else global_position
+	var normal: Vector2 = (center - global_position).normalized()
+	var position: Vector2 = global_position
+	var direct_state := PhysicsServer2D.body_get_direct_state(get_rid())
+	if direct_state != null:
+		for index: int in direct_state.get_contact_count():
+			if direct_state.get_contact_collider_id(index) == body.get_instance_id():
+				var reported: Vector2 = direct_state.get_contact_local_normal(index)
+				if not reported.is_zero_approx():
+					normal = reported.normalized()
+					if normal.dot(center - global_position) < 0.0:
+						normal = -normal
+				position = direct_state.get_contact_local_position(index)
+				break
+	collided.emit(body, normal, position)
+
+
+func _on_body_exited(body: Node) -> void:
+	separated.emit(body)
 
 # ---------------------------------------------------------------------------
 # Internal build / apply