Add void enemy sound effects

[wjt]

The void-spreading enemies are currently silent, except for the "alerted" chime (borrowed from the stealth enemy).

I can think of several actions that could have a sound effect:

• Enemy motion (perhaps a softer sound when they are patrolling, e.g. https://freesound.org/people/nhaudio/sounds/177935/, and a stronger wind when they are chasing, e.g. https://freesound.org/people/felixdembinski/sounds/686043/)
• When props/tiles are consumed
• When StoryWeaver is caught and falls into the void

The sound effects will need to sit against the music so we should take this on after integrating the music.

XP Summary (total 375)

Subdomain	Skill	XP
Art: Music & Sound	Problem Solving	75
Art: Music & Sound	Creativity & Design Thinking	150
Art: Music & Sound	Technical Literacy	150