Add rustfmt configuration and reformat code

- Document new Rust formatting standards in AGENTS, CODE_MAP, and
  PROGRESS.
- Add rustfmt.toml with style 2024, 2‑space indents, 100‑char width, LF
  endings.
- Apply consistent 2‑space indentation and ordering across source files.
- Minor clean‑up of imports and whitespace to match the new style.

src/app/states/settings.rs

@@ -2,12 +2,12 @@ use crate::app::states::{PerkDecks, skirmish_states::GameMode};
 
 #[derive(Debug, Clone, PartialEq)]
 pub struct SettingsState {
-    pub username: String,
-    pub game_mode: GameMode,
-    pub perk_deck: PerkDecks,
-    pub starting_wood: u16,
-    pub starting_iron: u16,
-    pub supply_limit: u8,
-    pub xp_modifier: f32,
-    pub skill_points_limit: u16,
+  pub username: String,
+  pub game_mode: GameMode,
+  pub perk_deck: PerkDecks,
+  pub starting_wood: u16,
+  pub starting_iron: u16,
+  pub supply_limit: u8,
+  pub xp_modifier: f32,
+  pub skill_points_limit: u16,
 }