Do a pass over samples to check for idioms and best practices

[kainino0x]

This code is one of the first references for WebGPU code so we should really make sure it uses best practices wherever possible.

Some of the demos are quite large and might be a lot of work to make match best practices. If this is the case we could "demote" them to a later section with a disclaimer that they're not necessarily good code to copy?