Add test for list<string> key type preserved through ArrayIterator

Adds a test case from phpstan.org/r/c448c867 verifying that when a
list<string> is passed to new ArrayIterator(), the inferred key type
is int<0, max> (not generalized to int).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: phpstan-bot

tests/PHPStan/Analyser/nsrt/bug-12601.php

@@ -24,6 +24,20 @@ public function getIterator(): Traversable
 	}
 }
 
+class HelloWorld3
+{
+	/** @var ArrayIterator<int, string> */
+	private ArrayIterator $a;
+
+	/** @param list<string> $map */
+	public function __construct(private array $map) {
+		$a = new ArrayIterator($this->map);
+		assertType('ArrayIterator<int<0, max>, string>', $a);
+
+		$this->a = $a;
+	}
+}
+
 /** @implements IteratorAggregate<int<0, max>, non-empty-string> */
 class HelloWorld2 implements IteratorAggregate
 {