Shrink board cells to 36px with tighter gaps on <768px screens so the
board fits on 375px phones. Add DataIgnoreMorph to the C4 chat input
so typing isn't disrupted when new messages arrive.
Add real-time chat alongside the game board, mirroring the snake chat
implementation. Fix mobile layout for both C4 and snake chats — expand
chat to full width and reduce history height on small screens.