feat: add stealth mode and enhance undetected browser support

- Add playwright-stealth integration with enable_stealth parameter in BrowserConfig
- Merge undetected browser strategy into main async_crawler_strategy.py using adapter pattern
- Add browser adapters (BrowserAdapter, PlaywrightAdapter, UndetectedAdapter) for flexible browser switching
- Update install.py to install both playwright and patchright browsers automatically
- Add comprehensive documentation for anti-bot features (stealth mode + undetected browser)
- Create examples demonstrating stealth mode usage and comparison tests
- Update pyproject.toml and requirements.txt with patchright>=1.49.0 and other dependencies
- Remove duplicate/unused dependencies (alphashape, cssselect, pyperclip, shapely, selenium)
- Add dependency checker tool in tests/check_dependencies.py

Breaking changes: None - all existing functionality preserved

🤖 Generated with [Claude Code](https://claude.ai/code)

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

requirements.txt

@@ -1,32 +1,33 @@
 # Note: These requirements are also specified in pyproject.toml
 # This file is kept for development environment setup and compatibility
+aiofiles>=24.1.0
+aiohttp>=3.11.11
 aiosqlite~=0.20
+anyio>=4.0.0
 lxml~=5.3
 litellm>=1.53.1
 numpy>=1.26.0,<3
 pillow>=10.4
 playwright>=1.49.0
+patchright>=1.49.0
 python-dotenv~=1.0
 requests~=2.26
 beautifulsoup4~=4.12
 tf-playwright-stealth>=1.1.0
 xxhash~=3.4
 rank-bm25~=0.2
-aiofiles>=24.1.0
 colorama~=0.4
 snowballstemmer~=2.2
 pydantic>=2.10
 pyOpenSSL>=24.3.0
 psutil>=6.1.1
+PyYAML>=6.0
 nltk>=3.9.1
 rich>=13.9.4
-cssselect>=1.2.0
 chardet>=5.2.0
 brotli>=1.1.0
 httpx[http2]>=0.27.2
 sentence-transformers>=2.2.0
-alphashape>=1.3.1
-shapely>=2.0.0
 
 fake-useragent>=2.2.0
 pdf2image>=1.17.0