Enhance Markdown generation and external content control

- Integrate customized html2text library for flexible Markdown output
- Add options to exclude external links and images
- Improve content scraping efficiency and error handling
- Update AsyncPlaywrightCrawlerStrategy for faster closing
- Enhance CosineStrategy with generic embedding model loading

crawl4ai/html2text/elements.py

@@ -0,0 +1,18 @@
+from typing import Dict, Optional
+
+
+class AnchorElement:
+    __slots__ = ["attrs", "count", "outcount"]
+
+    def __init__(self, attrs: Dict[str, Optional[str]], count: int, outcount: int):
+        self.attrs = attrs
+        self.count = count
+        self.outcount = outcount
+
+
+class ListElement:
+    __slots__ = ["name", "num"]
+
+    def __init__(self, name: str, num: int):
+        self.name = name
+        self.num = num