Runtime hygiene: fix RefCounted cycles (clean suite exit), full-length shifts, wand cooldown

- FSM holds owner via WeakRef; ShiftCoordinator is RefCounted (logic-only);
  persistence tests free the Save node -> test suite exits with zero
  'resources still in use' warnings (was ~13) and 57/57 pass
- GameManager uses each scenario's shift_duration_s (900s ~ 10-15 min) for
  real shifts instead of the 300s test duration
- Wand screening gets a 0.8s recharge cooldown with a wand.recharge message
- TODO/DONE/MEMORY/README synced

src/core/fsm.gd

@@ -2,15 +2,26 @@ class_name FSM
 extends RefCounted
 ## Minimal generic finite state machine used by NPCController and ShiftCoordinator.
 ## Deterministic and headless-testable.
+##
+## The owner is held through a WeakRef so long-lived owners do not create a
+## reference cycle (FSM <-> owner), which previously leaked RefCounted objects
+## at process exit (see MEMORY.md).
 
 signal state_changed(node: Object, from_state: String, to_state: String)
 
 var current_state: String = ""
 var _transitions: Dictionary = {} # state_name -> Array[{to, guard: Callable}]
-var _owner_node: Object = null
+var _owner_ref: WeakRef = null
 
 func _init(owner_node: Object = null) -> void:
-	_owner_node = owner_node
+	if owner_node != null:
+		_owner_ref = weakref(owner_node)
+
+## The live owner object, or null if it was freed.
+func _owner() -> Object:
+	if _owner_ref == null:
+		return null
+	return _owner_ref.get_ref() as Object
 
 ## Register a transition. guard is an optional Callable(node) -> bool.
 func add_transition(from_state: String, to_state: String, guard: Callable = Callable()) -> void:
@@ -20,7 +31,7 @@ func add_transition(from_state: String, to_state: String, guard: Callable = Call
 
 func start(initial_state: String) -> void:
 	current_state = initial_state
-	state_changed.emit(_owner_node, "", initial_state)
+	state_changed.emit(_owner(), "", initial_state)
 
 ## Attempt to move to `to_state`. Returns true when executed.
 func transition_to(to_state: String) -> bool:
@@ -31,10 +42,10 @@ func transition_to(to_state: String) -> bool:
 		if t["to"] != to_state:
 			continue
 		var guard: Callable = t["guard"]
-		if not guard.is_valid() or guard.call(_owner_node):
+		if not guard.is_valid() or guard.call(_owner()):
 			var from := current_state
 			current_state = to_state
-			state_changed.emit(_owner_node, from, to_state)
+			state_changed.emit(_owner(), from, to_state)
 			return true
 	return false
 
@@ -42,6 +53,6 @@ func can_transition_to(to_state: String) -> bool:
 	for t in _transitions.get(current_state, []):
 		if t["to"] == to_state:
 			var guard: Callable = t["guard"]
-			if not guard.is_valid() or guard.call(_owner_node):
+			if not guard.is_valid() or guard.call(_owner()):
 				return true
 	return false

src/core/shift_coordinator.gd

@@ -1,5 +1,5 @@
 class_name ShiftCoordinator
-extends Node
+extends RefCounted
 
 const Rules := preload("res://src/core/rules.gd")
 const EventBus := preload("res://src/core/event_bus.gd")