feat(dispose): add debug checks for double disposal

Added debug-only checks in Dispose methods of HashMapHelper, UnTypedArray, and UnsafeArray to log a message (with optional stack trace) if Dispose is called on an uninitialized or already disposed instance, unless the buffer is null. Incremented assembly version to 1.6.6.

Misaki.HighPerformance.LowLevel/Collections/UnsafeArray.cs

@@ -418,6 +418,12 @@ public unsafe struct UnsafeArray<T> : IUnsafeCollection<T>
     {
         if (!IsCreated)
         {
+#if DEBUG
+            if (_buffer == null)
+            {
+                return;
+            }
+
             var message = "The UnsafeArray is not created or already disposed.";
 #if MHP_ENABLE_STACKTRACE
             var stackTrace = new StackTrace(1, true);
@@ -435,6 +441,7 @@ public unsafe struct UnsafeArray<T> : IUnsafeCollection<T>
             message += Environment.NewLine + sb.ToString();
 #endif
             Debug.WriteLine(message);
+#endif
             return;
         }