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>

docs/md_v2/core/browser-crawler-config.md

@@ -29,6 +29,7 @@ class BrowserConfig:
         text_mode=False,
         light_mode=False,
         extra_args=None,
+        enable_stealth=False,
         # ... other advanced parameters omitted here
     ):
         ...
@@ -84,6 +85,11 @@ class BrowserConfig:
     - Additional flags for the underlying browser.  
     - E.g. `["--disable-extensions"]`.
 
+11. **`enable_stealth`**:  
+    - If `True`, enables stealth mode using playwright-stealth.  
+    - Modifies browser fingerprints to avoid basic bot detection.  
+    - Default is `False`. Recommended for sites with bot protection.
+
 ### Helper Methods
 
 Both configuration classes provide a `clone()` method to create modified copies: