Add scripts for capturing network responses and extracting document content

- Implement capture_with_cdp.py to capture all network response bodies using Chrome DevTools Protocol.
- Create extract_sections.py to extract sections from STATdx snapshot HTML files into JSON Lines.
- Add unpack_document_content.py to extract `documentHtml` from captured JSON bodies and save as HTML files.
- Update .gitignore to include playwright_profile.

.gitignore

@@ -66,6 +66,7 @@ secrets.json
 
 .chrome_profile
 .playwright_profile
+playwright_profile
 
 captured/
 xhr_captured/