Add prop interaction system and throw mechanics specification

- Introduced `stickman_prop_interactor.gd` to manage prop interactions.
- Created `phase_11_prop_interactions.md` detailing the design and implementation of prop pickup, drop, and throw mechanics.
- Defined interaction states, action lifecycles, and event triggers for prop handling.
- Specified constraints for throw actions, including target positioning and velocity calculations.
- Established acceptance criteria for prop interactions and lifecycle management.

scripts/trigger_registry.gd

@@ -32,6 +32,21 @@ 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",
+	},
 }