Implement interactive prop handling for StickmanRig

- Added PropTrajectory class for deterministic ballistic calculations.
- Introduced StickmanPropInteraction component to manage prop interactions (pickup, drop, throw).
- Implemented grip resolution and attachment logic for props.
- Added signals for interaction events (prop_picked_up, prop_dropped, prop_thrown).
- Defined specifications for prop interaction lifecycle and event rules.
- Ensured compatibility with existing prop systems and added new capabilities for prop pickup.

scripts/trigger_registry.gd

@@ -32,6 +32,9 @@ const TRIGGER_TEMPLATES := {
 		"icon": "💥",
 		"target_type": "prop",
 	},
+	"prop_picked_up": { "label": "Picks up a prop", "icon": "🖐️", "target_type": "prop" },
+	"prop_dropped": { "label": "Drops a prop", "icon": "⬇️", "target_type": "prop" },
+	"prop_thrown": { "label": "Throws a prop", "icon": "🎯", "target_type": "prop" },
 }