Reserve index 0 in SlotMap, improve unsafe collections

- Reserve index 0 as always invalid in SlotMap, ConcurrentSlotMap, UnsafeSlotMap, and UnsafeSparseSet; update all index checks and slot operations accordingly
- Refactor SlotMap to use parallel arrays and BitArray for occupancy
- Double capacity on resize for all major unsafe collections
- Add debugger display support for unsafe collections
- Improve NuGet publishing workflow to skip existing versions
- Increment package versions (LowLevel: 1.3.1, main: 1.0.2)
- Add comprehensive unit tests for SlotMap and ConcurrentSlotMap
- Update main program and documentation for new slot map behavior

Misaki.HighPerformance.LowLevel/Collections/UnsafeQueue.cs

@@ -110,7 +110,7 @@ public unsafe struct UnsafeQueue<T> : IUnsafeCollection<T>
     {
         if (_count >= Capacity)
         {
-            Resize((int)(Capacity * 1.5f));
+            Resize(Math.Max(1, Capacity * 2));
         }
 
         UnsafeUtility.WriteArrayElement(_array.GetUnsafePtr(), (_offset + _count) % Capacity, value);