Update formatting to use 4‑space indentation

- Adjust rustfmt.toml to set tab_spaces = 4.
- Reformat imports, struct definitions, function bodies, and match arms
  across the project to match the new style (aligned fields, added
  spacing, etc.).
- Ensure all code complies with the updated rustfmt settings.

src/app/state.rs

@@ -1,66 +1,66 @@
 use crate::{
-  app::states::{
-    MainMenuState, PerkDecksState, SettingsState, SkillsConfigState, SkirmishState,
-    skirmish_states::{BoardState, Resources},
-  },
-  cli::Cli,
+    app::states::{
+        MainMenuState, PerkDecksState, SettingsState, SkillsConfigState, SkirmishState,
+        skirmish_states::{BoardState, Resources},
+    },
+    cli::Cli,
 };
 use ratatui::layout::Rect;
 
 #[derive(Debug, Clone, PartialEq)]
 pub struct GameStates {
-  pub main_menu: MainMenuState,
-  pub skirmish: SkirmishState,
-  pub perk_decks: PerkDecksState,
-  pub skills_config: SkillsConfigState,
-  pub settings: SettingsState,
+    pub main_menu: MainMenuState,
+    pub skirmish: SkirmishState,
+    pub perk_decks: PerkDecksState,
+    pub skills_config: SkillsConfigState,
+    pub settings: SettingsState,
 }
 
 impl GameStates {
-  pub fn new(args: &Cli, area: &Rect) -> Self {
-    Self {
-      main_menu: MainMenuState {
-        id: 0,
-        name: "Main Menu",
-        selected_view: 1,
-      },
-      skirmish: SkirmishState {
-        id: 1,
-        name: "Skirmish",
-        board: BoardState::new(
-          area,
-          args.map_width as usize,
-          args.map_height as usize,
-          args.zoom_level,
-          false,
-        ),
-        side_panel: false,
-        turn_counter: 0,
-        player_resources: Resources::new(args.starting_wood, args.starting_metal),
-        enemy_resources: Resources::new(args.starting_wood, args.starting_metal),
-        building_view: false,
-        recruitment_view: false,
-      },
-      perk_decks: PerkDecksState {
-        id: 2,
-        name: "Perk Decks",
-        selected_perk_deck: 0,
-      },
-      skills_config: SkillsConfigState {
-        id: 3,
-        name: "Skills Config",
-        selected_skill: 0,
-      },
-      settings: SettingsState {
-        username: args.username.clone(),
-        game_mode: args.game_mode.clone(),
-        perk_deck: args.perk_deck.clone(),
-        starting_wood: args.starting_wood.clone(),
-        starting_metal: args.starting_metal,
-        supply_limit: args.supply_limit.clone(),
-        xp_modifier: args.xp_modifier.clone(),
-        skill_points_limit: args.skill_points_limit.clone(),
-      },
+    pub fn new(args: &Cli, area: &Rect) -> Self {
+        Self {
+            main_menu: MainMenuState {
+                id: 0,
+                name: "Main Menu",
+                selected_view: 1,
+            },
+            skirmish: SkirmishState {
+                id: 1,
+                name: "Skirmish",
+                board: BoardState::new(
+                    area,
+                    args.map_width as usize,
+                    args.map_height as usize,
+                    args.zoom_level,
+                    false,
+                ),
+                side_panel: false,
+                turn_counter: 0,
+                player_resources: Resources::new(args.starting_wood, args.starting_metal),
+                enemy_resources: Resources::new(args.starting_wood, args.starting_metal),
+                building_view: false,
+                recruitment_view: false,
+            },
+            perk_decks: PerkDecksState {
+                id: 2,
+                name: "Perk Decks",
+                selected_perk_deck: 0,
+            },
+            skills_config: SkillsConfigState {
+                id: 3,
+                name: "Skills Config",
+                selected_skill: 0,
+            },
+            settings: SettingsState {
+                username: args.username.clone(),
+                game_mode: args.game_mode.clone(),
+                perk_deck: args.perk_deck.clone(),
+                starting_wood: args.starting_wood.clone(),
+                starting_metal: args.starting_metal,
+                supply_limit: args.supply_limit.clone(),
+                xp_modifier: args.xp_modifier.clone(),
+                skill_points_limit: args.skill_points_limit.clone(),
+            },
+        }
     }
-  }
 }