refactor(input): LevelId direct field access instead of dereference

Replace double dereferencing with direct field access in `input.rs`,
`level.rs`, and `ui.rs` to simplify code and improve readability.

src/systems/input.rs

@@ -443,7 +443,7 @@ pub fn file_drag_and_drop(
                 Ok(levels) => {
                     info!("Done, {} levels loaded", levels.len());
                     database.import_levels(&levels);
-                    **level_id = database.get_level_id(&levels[0]).unwrap();
+                    level_id.0 = database.get_level_id(&levels[0]).unwrap();
                 }
                 Err(msg) => warn!("Failed to load levels from file: {}", msg),
             }

src/systems/level.rs

@@ -61,7 +61,7 @@ pub fn spawn_board(
     mut spritesheet_layouts: ResMut<Assets<TextureAtlasLayout>>,
 ) {
     let database = database.lock().unwrap();
-    let level = database.get_level_by_id(**level_id).unwrap();
+    let level = database.get_level_by_id(level_id.0).unwrap();
 
     let spritesheet_handle = asset_server.load("textures/tilesheet.png");
     let tile_size = Vector2::new(128.0, 128.0);
@@ -151,11 +151,11 @@ pub fn auto_switch_to_next_unsolved_level(
     let board = &mut board.single_mut().board;
     debug_assert!(board.is_solved());
     info!("{}", "=".repeat(15));
-    info!("#{} Sloved!", **level_id);
+    info!("#{} Sloved!", level_id.0);
     info!("Moves   : {}", board.actions().moves());
     info!("Pushes  : {}", board.actions().pushes());
     info!("Solution: {}", board.actions().to_string());
-    database.update_solution(**level_id, board.actions());
+    database.update_solution(level_id.0, board.actions());
     switch_to_next_unsolved_level(&mut level_id, &database);
 }
 
@@ -170,7 +170,7 @@ pub fn import_from_clipboard(level_id: &mut LevelId, database: &database::Databa
             }
             info!("import {} levels from clipboard", levels.len());
             database.import_levels(&levels);
-            **level_id = database.get_level_id(&levels[0]).unwrap();
+            level_id.0 = database.get_level_id(&levels[0]).unwrap();
         }
         Err(msg) => error!("failed to import levels from clipboard: {}", msg),
     }
@@ -199,14 +199,14 @@ pub fn switch_to_previous_unsolved_level(level_id: &mut LevelId, database: &data
 
 /// Switches to the next level based on the current level ID.
 pub fn switch_to_next_level(level_id: &mut LevelId, database: &database::Database) {
-    if **level_id < database.max_level_id().unwrap() {
-        **level_id += 1;
+    if level_id.0 < database.max_level_id().unwrap() {
+        level_id.0 += 1;
     }
 }
 
 /// Switches to the previous level based on the current level ID.
 pub fn switch_to_previous_level(level_id: &mut LevelId, database: &database::Database) {
-    if **level_id > database.min_level_id().unwrap() {
-        **level_id -= 1;
+    if level_id.0 > database.min_level_id().unwrap() {
+        level_id.0 -= 1;
     }
 }

src/systems/ui.rs

@@ -73,20 +73,20 @@ pub fn update_hud(
     let board = &board.single().board;
 
     if level_id.is_changed() {
-        hud.sections[1].value = format!("#{}\n", **level_id);
+        hud.sections[1].value = format!("#{}\n", level_id.0);
 
         let database = database.lock().unwrap();
         hud.sections[7].value = format!(
             "{}\n",
             database
-                .best_move_solution(**level_id)
+                .best_move_solution(level_id.0)
                 .unwrap_or_default()
                 .moves()
         );
         hud.sections[9].value = format!(
             "{}\n",
             database
-                .best_push_solution(**level_id)
+                .best_push_solution(level_id.0)
                 .unwrap_or_default()
                 .pushes()
         );