fix: allow single-label hostnames in deep crawling

[rozin-not-found]

Summary

Fixes #2079.

This PR updates the URL validation logic in the deep crawling strategies to accept valid single-label hostnames. Previously, can_process_url() strictly required a period (.) in the network location (netloc). This incorrectly rejected local development servers (e.g., http://localhost:8080) and internal Docker services. This strict check has been removed while maintaining the essential scheme and netloc presence validations.

List of files changed and why

• crawl4ai/deep_crawling/bfs_strategy.py: Removed the "." not in parsed.netloc check to allow dotless domains.
• crawl4ai/deep_crawling/bff_strategy.py: Removed the identical dot requirement for consistency across strategies.

How Has This Been Tested?

• Created a local reproduction script to test can_process_url() against single-label hostnames like http://localhost:8080.
• Verified the methods now accept these URLs without raising a ValueError, while still properly rejecting completely invalid formats.

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added/updated unit tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes