removed hardcoded max iframe recursion limit (#3039)

    
<!-- This is an auto-generated description by cubic. -->

## Summary by cubic
Removed the fixed 30-level recursion limit in the DOM serializer so deep
iframe and shadow DOM trees are no longer truncated. This enables full
traversal and fixes missing elements in deeply nested pages.

<!-- End of auto-generated description by cubic. -->

Author: gregpr07

browser_use/dom/serializer/serializer.py

@@ -127,10 +127,6 @@ def _is_interactive_cached(self, node: EnhancedDOMTreeNode) -> bool:
 	def _create_simplified_tree(self, node: EnhancedDOMTreeNode, depth: int = 0) -> SimplifiedNode | None:
 		"""Step 1: Create a simplified tree with enhanced element detection."""
 
-		# Prevent infinite recursion by limiting depth to 30 levels
-		if depth > 30:
-			return None
-
 		if node.node_type == NodeType.DOCUMENT_NODE:
 			# for all cldren including shadow roots
 			for child in node.children_and_shadow_roots: