refactor: remove legacy parser system and migrate to unified engine

- Remove internal/parser package and all legacy ID generation logic
- Update enhancer and auto_enhancer to use unified engine functions
- Migrate utility functions (FindViableChildren, HasEditableContent) to engine
- Create stub enhancer implementation that uses unified engine architecture
- Ensure all enhancement workflows now go through single unified system
- Remove parser dependencies and consolidate content processing logic

This completes the cleanup phase - all components now use unified engine
instead of fragmented ID generation systems.

internal/engine/utils.go

@@ -267,7 +267,37 @@ func isSelfClosing(node *html.Node) bool {
 	return selfClosingTags[node.Data]
 }
 
-// Note: FindElementInDocument functions removed - will be reimplemented in engine if needed
+// FindElementInDocument finds an element in HTML document tree using content matching
+func FindElementInDocument(doc *html.Node, tag, content string) *html.Node {
+	return findElementWithContent(doc, tag, content)
+}
+
+// findElementWithContent uses content-based matching to find the correct element
+func findElementWithContent(node *html.Node, targetTag, targetContent string) *html.Node {
+	normalizedTarget := strings.TrimSpace(targetContent)
+
+	if node.Type == html.ElementNode && node.Data == targetTag {
+		classes := GetClasses(node)
+		if ContainsClass(classes, "insertr") {
+			// Content-based validation for precise matching
+			textContent := extractTextContent(node)
+			nodeContent := strings.TrimSpace(textContent)
+
+			if nodeContent == normalizedTarget {
+				return node
+			}
+		}
+	}
+
+	// Recursively search children
+	for child := node.FirstChild; child != nil; child = child.NextSibling {
+		if result := findElementWithContent(child, targetTag, normalizedTarget); result != nil {
+			return result
+		}
+	}
+
+	return nil
+}
 
 // GetAttribute gets an attribute value from an HTML node (exported version)
 func GetAttribute(node *html.Node, key string) string {