test(room-navigator): add missing is_at_home and go_to_hospital tests

Adds 7 new test cases covering home/hospital navigation state:
- is_at_home() initial state and transitions
- go_to_home() with idempotence check
- go_to_hospital() state restoration and guards
- is_at_home flag cleanup on room navigation

Implements corresponding methods in RoomNavigator:
- is_at_home(): Returns home state
- go_to_home(): Navigates to home (0,0) and saves hospital position
- go_to_hospital(): Returns to previously saved hospital location
- _go_to_room_internal(): Helper to avoid flag interference

All 34 tests passing.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

scripts/systems/room_navigator.gd

@@ -10,6 +10,9 @@ const CAMERA_TWEEN_DURATION: float = 0.6
 var _current_floor: int = 0
 var _current_room: int = 0
 var _camera: Camera2D
+var _is_at_home: bool = false
+var _last_hospital_floor: int = 0
+var _last_hospital_room: int = 0
 
 
 func initialize(camera: Camera2D) -> void:
@@ -21,6 +24,12 @@ func go_to_floor(floor_index: int) -> void:
 
 
 func go_to_room(floor_index: int, room_index: int) -> void:
+	_go_to_room_internal(floor_index, room_index, true)
+
+
+func _go_to_room_internal(floor_index: int, room_index: int, clear_home_flag: bool) -> void:
+	if clear_home_flag:
+		_is_at_home = false
 	if _camera == null:
 		return
 	if floor_index == _current_floor and room_index == _current_room:
@@ -42,3 +51,23 @@ func get_current_floor() -> int:
 
 func get_current_room() -> int:
 	return _current_room
+
+
+func is_at_home() -> bool:
+	return _is_at_home
+
+
+func go_to_home() -> void:
+	if _is_at_home:
+		return
+	_last_hospital_floor = _current_floor
+	_last_hospital_room = _current_room
+	_is_at_home = true
+	_go_to_room_internal(0, 0, false)
+
+
+func go_to_hospital() -> void:
+	if not _is_at_home:
+		return
+	_is_at_home = false
+	go_to_room(_last_hospital_floor, _last_hospital_room)