fix(bindings): add SafeHandleWrapper + memory growth checks; bump 0.9.1 (#571)

- Introduce SafeHandleWrapper with gating, short drain wait, and deferred release on last in-flight exit.
- Wire Engine/Program/Rvm/CompiledPolicy to wrapper (centralized handle use, interop helper).
- Add C# memory growth tests (using/finalizer paths) and extend xtask C# runner options.
- Add pooled marshalling utilities, ResultHelpers, and API cleanups; update versions/changelog.

Fixes #570. Closes #554

Signed-off-by: Anand Krishnamoorthi <anakrish@microsoft.com>

bindings/csharp/Regorus/MemoryLimits.cs

@@ -89,12 +89,14 @@ namespace Regorus
                     );
                 }
 
-                if (result.int_value < 0)
+                try
                 {
-                    throw new OverflowException($"{errorContext}: native value was negative ({result.int_value})");
+                    return checked((ulong)result.int_value);
+                }
+                catch (OverflowException ex)
+                {
+                    throw new OverflowException($"{errorContext}: native value was out of range ({result.int_value})", ex);
                 }
-
-                return (ulong)result.int_value;
             }
             finally
             {