fix(scripting): resolve Medium code-review finding (Core.Scripting-007)

In TimedScriptEvaluator.RunAsync, the catch (TimeoutException) block
now checks ct.IsCancellationRequested before throwing
ScriptTimeoutException, so a caller cancellation that races a timeout
deterministically surfaces as OperationCanceledException regardless of
which WaitAsync observes first. Regression test
Caller_cancellation_wins_even_when_timeout_fires_first added.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/Core/ZB.MOM.WW.OtOpcUa.Core.Scripting/TimedScriptEvaluator.cs

@@ -76,6 +76,14 @@ public sealed class TimedScriptEvaluator<TContext, TResult>
             // WaitAsync's synthesized timeout — the inner task may still be running
             // on its thread-pool thread (known leak documented in the class summary).
             // Wrap so callers can distinguish from user-written timeout logic.
+            //
+            // The class docs guarantee "caller-supplied cancel wins over timeout".
+            // When both fire at nearly the same time, WaitAsync observes them in
+            // non-deterministic order, so a cancel that arrives a few µs after the
+            // timeout still reaches here as TimeoutException. Re-check the token so
+            // the guarantee holds regardless of race ordering. (Core.Scripting-007.)
+            if (ct.IsCancellationRequested)
+                throw new OperationCanceledException(ct);
             throw new ScriptTimeoutException(Timeout);
         }
     }