Bug fix and small update

Bug Fix:
Ensure that the next level can be generated correctly.

Minor Updates:

When the power supply of the house equals the required power, the number in the upper right corner will turn green.

A sound effect will play when the mouse hovers over the house.

A display showing the number of connected units has been added to the upper right corner of the tunnel.

demo can play here : https://indigogame.itch.io/cat-engineer-electricity-adventure