investigate `gameplayFrames`

we're setting/resetting `gameplayFrames` to `0` in a few places, it'd be good to get a better grasp on when/how that happened on original hardware and if there are situations where we need to set/reset it beyond those times

from https://github.com/HarbourMasters/Shipwright/pull/4984#discussion_r1938420757:
> I know this is just copying what we had before, but I figure it's worth pointing out that this is not accurate to what it is actually happening: which is that this is resetting the frame count on any play destroy with the debug save loaded (title screen or LRZ).
>
> I think the intent for the frame reset is to happen when ever we transition from a non-PlayState game state to a PlayState game state.
>
> Not something we need to do in this PR, but should at least track an issue for investigation (e.g. test with hardware)

https://github.com/HarbourMasters/Shipwright/pull/4984#discussion_r1938421931 (reply):

> yeah, i didn't want to go down the rabbit hole of that (and autosave stuff) when moving it over (it originally came from #1792, and there's more `gameplayFrames` stuff in #3389 too)