Refactor: reorganize scripts with domain-driven design structure

Move all C# scripts from flat structure to organized folders:
- Core/ for game logic (Game, GameState, GameSettings)
- UI/Menus/ and UI/Dialogs/ for user interface
- Systems/ for reusable systems (Save, Localization)
- Data/ for data models and configuration
- Added framework for future: Gameplay/, Story/, Modding/

Update all .tscn scene files to reference new script paths.
Fix timing issue in AdvancedSaveDialog focus handling.

scripts/Data/GameSeed.cs

@@ -0,0 +1,55 @@
+using System;
+
+namespace TheGame
+{
+    public class GameSeed
+    {
+        public string SeedValue { get; set; }
+        public DateTime CreatedDate { get; set; }
+        public string DisplayName { get; set; }
+        
+        public GameSeed()
+        {
+            SeedValue = GenerateNewSeed();
+            CreatedDate = DateTime.Now;
+            DisplayName = $"Game {CreatedDate:yyyy-MM-dd HH:mm}";
+        }
+        
+        public GameSeed(string customSeed, string displayName = "")
+        {
+            SeedValue = customSeed;
+            CreatedDate = DateTime.Now;
+            DisplayName = string.IsNullOrEmpty(displayName) ? $"Game {CreatedDate:yyyy-MM-dd HH:mm}" : displayName;
+        }
+        
+        private static string GenerateNewSeed()
+        {
+            // Generera en 8-tecken seed baserad på timestamp och random
+            var random = new Random();
+            var timestamp = DateTime.Now.Ticks;
+            var combined = timestamp + random.Next(1000, 9999);
+            
+            // Konvertera till hexadecimal och ta första 8 tecknen
+            return Math.Abs(combined).ToString("X")[..8];
+        }
+        
+        public override string ToString()
+        {
+            return $"{DisplayName} (Seed: {SeedValue})";
+        }
+        
+        public override bool Equals(object obj)
+        {
+            if (obj is GameSeed other)
+            {
+                return SeedValue.Equals(other.SeedValue);
+            }
+            return false;
+        }
+        
+        public override int GetHashCode()
+        {
+            return SeedValue.GetHashCode();
+        }
+    }
+}

scripts/Data/GameSeed.cs.uid

@@ -0,0 +1 @@
+uid://bibp6hpk275ab