long ids but not long enough!

- Object and prefab file id loading
- Generate grid update
- Switched uint to long but should probably be ulong!

Runtime/SceneGrid.cs

@@ -14,16 +14,16 @@ namespace VertexColor.ScenePartition.Editor
 
         public SceneGridDictionary Grid => grid;
 
-        public void Insert(uint id, Vector3 point)
+        public void Insert(long scenePartitionId, Vector3 point)
         {
             int gridId = CalculateGridPosition(point, cellSize);
-            if (grid.TryGetValue(gridId, out List<uint> ids))
+            if (grid.TryGetValue(gridId, out List<long> ids))
             {
-                ids.Add(id);
+                ids.Add(scenePartitionId);
             }
             else
             {
-                grid.Add(gridId, new List<uint> { id });
+                grid.Add(gridId, new List<long> { scenePartitionId });
             }
         }
 
@@ -49,5 +49,20 @@ namespace VertexColor.ScenePartition.Editor
 
             return (x, y);
         }
+
+        public static long LongPairToLong(long x, long y)
+        {
+            // Combine x and y components into a single long
+            return (x << 32) | (uint)y;
+        }
+
+        public static (long, long) LongToLongPair(long value)
+        {
+            // Extract x and y components from the combined long
+            long x = value >> 32;
+            long y = (uint)value;
+
+            return (x, y);
+        }
     }
 }