Reorganize dispatcher functionality into separate components:
- Create dedicated dispatcher classes (MemoryAdaptive, Semaphore)
- Add RateLimiter for smart request throttling
- Implement CrawlerMonitor for real-time progress tracking
- Move dispatcher config from CrawlerRunConfig to separate classes
BREAKING CHANGE: Dispatcher configuration moved from CrawlerRunConfig to dedicated dispatcher classes. Users need to update their configuration approach for multi-URL crawling.
