Address review: add IntersectionType comment in DateTimeModifyReturnTypeExtension

Restore TypeTraverser approach (TypeCombinator::intersect creates
Bar&DateTimeInterface intersections instead of filtering them out).
Add explicit comment explaining that IntersectionType is evaluated
as a whole via isSuperTypeOf and doesn't need special traversal.

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

Author: phpstan-bot

src/Type/Php/DateTimeModifyReturnTypeExtension.php

@@ -94,6 +94,8 @@ static function (Type $type, callable $traverse) use ($dateTimeInterfaceType): T
 					if ($type instanceof UnionType) {
 						return $traverse($type);
 					}
+					// IntersectionType and other composite types are evaluated
+					// as a whole via isSuperTypeOf — no need to traverse into them
 					if ($dateTimeInterfaceType->isSuperTypeOf($type)->yes()) {
 						return $type;
 					}