Total mod overhaul for split-screen support

[Xemrox]

fixes all known split-screen bugs (#4) and releases as 1.9.0

[mishahawthorn]

@Xemrox I'll review this week, thank you for the significant contribution!

[mishahawthorn]

@Xemrox thank you again for the contribution! This PR introduces use of better conventions throughout and overall greatly improves the health of the project.

I did observe one potential regression which I'd be curious if you are able to reproduce, or clarify if the intention is to introduce different behavior here. When testing a local co-op scenario I found that opening the menu to pause would pause time for all users with this PR, where the 1.8.1 tag does behave as expected. (Mostly 😅 The "X" is not showing as expected, a bug in the current revision)

1.8.1 (current)
https://github.com/user-attachments/assets/600ffb39-a0d5-4100-94b1-b5080c6c3cdb

1.9.0 (proposed)
https://github.com/user-attachments/assets/b6f8656c-0b92-49bd-98c9-e99aea60fd2b

[Xemrox]

hey thanks for the feedback. I didn't notice the regression as I am using it solely on local co-op and didn't use the old version much. What would be the expected behavior? Maybe I've fixed a bug without knowing.
From what I can tell as soon as one of the players opens his menu the game pauses. In vanilla gameplay that happens only if both players open their menu.

Aside from that I've left a debug hotkey and a few verbose message changes in the mod which I like to remove first.
On top of that after playing with the mod for quite a few hous (50+) I can relate to a user who requested to be able to toggle all features. So I'll propably work on this next #9
One bug though which is very hard to reproduce that I encountered is related to the skullcaverns and sometimes mines.
From time to time on entering the mines the (second-only?) player HP gets reset (?) to 0/1 (can't tell the difference),
which looks like some kind of unset variable. Gonna investigate that but no clue at the moment.

[mishahawthorn]

Apologies for my delayed response, life got busy. Haven't had much time to play either 😔. Will take another look in the next week or so and see if we can get this merged! Thanks again @Xemrox!

[ath88]

One bug though which is very hard to reproduce that I encountered is related to the skullcaverns and sometimes mines. From time to time on entering the mines the (second-only?) player HP gets reset (?) to 0/1 (can't tell the difference), which looks like some kind of unset variable. Gonna investigate that but no clue at the moment.

Seems like this bug is likely not a new one: https://www.nexusmods.com/stardewvalley/mods/21327/?tab=forum&topic_id=14176228

I'd love to be able to toggle pausing when any player has a pause-condition, rather than all players having it. :) I'll wait with trying to implement this until this PR is merged, as it seems I'll have to handle quite a few conflicts if not.

[mishahawthorn]

until this PR is merged

I need to get out of the way here 😅 I have carved out time on my calendar to get another round of review this week!

[mishahawthorn]

Just did some playtesting with one other farmhand over LAN multiplayer and found that the co-op regression now applies to that multiplayer mode now. Regardless of the farmhand's pause state, the shared game time would pause exclusively based on the host's paused state. I'll dig in and take a closer look at the code, and I haven't validated local co-op again yet.