Create room 006 (Cave Entrance) and wire to room 005

- Added kq4_006_cave_entrance scene with west exit to room 005
- Updated room 005 to include target UID for room 006 transition
- Room 006 south exit to room 012 omitted (room 012 doesn't exist yet)
- Both transitions validated with exit checker

scenes/kq4_005_forest_grove/kq4_005_forest_grove.tscn

@@ -59,6 +59,7 @@ position = Vector2(174, 519)
 position = Vector2(1766, 74)
 polygon = PackedVector2Array(-108, 454, -87, 649, 376, 658, 348, 381)
 appear_at_node = "kq4_005_forest_grove"
+target = "uid://23orpd43hrwbt"
 label = "Cave Entrance"
 
 [node name="entrance" parent="kq4_006_cave_entrance" index="0"]