add log message for completion of all days in GameManager

rust/src/systems/game_manager.rs

@@ -109,6 +109,8 @@ impl GameManager {
         }
 
         if index >= self.days.len() as i32 {
+            godot_print!("GameManager: All days complete!");
+
             self.cleanup_level();
             if let Some(s) = &mut self.win_screen {
                 s.set_visible(false);