feat(monitor): add real-time crawler monitoring system with memory management

Implements a comprehensive monitoring and visualization system for tracking web crawler operations in real-time. The system includes:
- Terminal-based dashboard with rich UI for displaying task statuses
- Memory pressure monitoring and adaptive dispatch control
- Queue statistics and performance metrics tracking
- Detailed task progress visualization
- Stress testing framework for memory management

This addition helps operators track crawler performance and manage memory usage more effectively.

crawl4ai/__init__.py

@@ -33,13 +33,12 @@ from .content_filter_strategy import (
     LLMContentFilter,
     RelevantContentFilter,
 )
-from .models import CrawlResult, MarkdownGenerationResult
+from .models import CrawlResult, MarkdownGenerationResult, DisplayMode
+from .components.crawler_monitor import CrawlerMonitor
 from .async_dispatcher import (
     MemoryAdaptiveDispatcher,
     SemaphoreDispatcher,
     RateLimiter,
-    CrawlerMonitor,
-    DisplayMode,
     BaseDispatcher,
 )
 from .docker_client import Crawl4aiDockerClient