feat(browser-farm): Add Docker browser support for remote crawling

Implement initial MVP for Docker-based browser management in Crawl4ai, enabling
remote browser execution in containerized environments.

Key Changes:
- Add browser_farm module with Docker support components:
  * BrowserFarmService: Manages browser endpoints
  * DockerBrowser: Handles Docker browser communication
  * Basic health check implementation
  * Dockerfile with optimized Chrome/Playwright setup:
    - Based on python:3.10-slim for minimal size
    - Includes all required system dependencies
    - Auto-installs crawl4ai and sets up Playwright
    - Configures Chrome with remote debugging
    - Uses socat for port forwarding (9223)

- Update core components:
  * Rename use_managed_browser to use_remote_browser for clarity
  * Modify BrowserManager to support Docker mode
  * Add Docker configuration in BrowserConfig
  * Update context handling for remote browsers

- Add example:
  * hello_world_docker.py demonstrating Docker browser usage

Technical Details:
- Docker container exposes port 9223 (mapped to host:9333)
- Uses CDP (Chrome DevTools Protocol) for remote connection
- Maintains compatibility with existing managed browser features
- Simplified endpoint management for MVP phase
- Optimized Docker setup:
  * Minimal dependencies installation
  * Proper Chrome flags for containerized environment
  * Headless mode with GPU disabled
  * Security considerations (no-sandbox mode)

Testing:
- Extensive Docker configuration testing and optimization
- Verified with hello_world_docker.py example
- Confirmed remote browser connection and crawling functionality
- Tested basic health checks

This is the first step towards a scalable browser farm solution, setting up
the foundation for future enhancements like resource monitoring, multiple
browser instances, and container lifecycle management.

docs/examples/v0.3.74.overview.py

@@ -160,7 +160,7 @@ async def browser_management_example():
     print(f"Browser profile will be saved to: {user_data_dir}")
     
     async with AsyncWebCrawler(
-        use_managed_browser=True,
+        use_remote_browser=True,
         user_data_dir=user_data_dir,
         headless=False,
         verbose=True
@@ -221,7 +221,7 @@ async def api_example():
             },
             "crawler_params": {
                 "headless": True,
-                # "use_managed_browser": True
+                # "use_remote_browser": True
             },
             "cache_mode": "bypass",
             # "screenshot": True,