Title shows (0) moves made which isn't that helpful

[frostburn]

Description of the bug
In correspondence games it's possible for the title to change to "(0) moves made" which unnecessarily draws attention to an unattended browser tab.

To Reproduce
Steps to reproduce the behavior:

1. Go to an on ongoing correspondence game
2. Click to make a move
3. Leave tab open for some time
4. Title changes to "(0) moves made"

Expected behavior
The title doesn't change until the opponent actually makes a move.

Desktop:

• OS: Linux (Ubuntu)
• Browser: Chrome
• Version: 127.0.6533.99 (Official Build) (64-bit)

Possible leads on how to fix the issue
In Game.tsx check that the diff is non-zero before updating the dynamic title.