feat: add ROOM_USIZE constant

src/constants/extra.rs

@@ -270,10 +270,15 @@ pub const ROOM_VISUAL_PER_ROOM_SIZE_LIMIT: u32 = 500 * 1024;
 /// [`Room`]: crate::objects::Room
 pub const ROOM_SIZE: u8 = 50;
 
+/// ['ROOM_SIZE'] cast into a `usize`, for indexing convenience.
+///
+/// ['ROOM_SIZE']: self::ROOM_SIZE
+pub const ROOM_USIZE: usize = ROOM_SIZE as usize;
+
 /// The number of total tiles in each [`Room`] in the game
 ///
 /// [`Room`]: crate::objects::Room
-pub const ROOM_AREA: usize = (ROOM_SIZE as usize) * (ROOM_SIZE as usize);
+pub const ROOM_AREA: usize = ROOM_USIZE * ROOM_USIZE;
 
 /// Owner username of hostile non-player structures and creeps which occupy
 /// sector center rooms.