Refactor GameMode and Players into skirmish_states

Move the GameMode and Players enums from the top‑level states module
into the
skirmish_states submodule, add an Unclaimed variant to Players, and
update all
imports, trait implementations, and related logic accordingly. Adjust
the
durability percentage calculation to use u32 for safety.

src/app/states/settings.rs

@@ -1,4 +1,4 @@
-use crate::app::states::{GameMode, PerkDecks};
+use crate::app::states::{PerkDecks, skirmish_states::GameMode};
 
 #[derive(Debug, Clone, PartialEq)]
 pub struct SettingsState {