fix: strip port from URL domain in is_external_url comparison

[Br1an67]

Summary

is_external_url() compared parsed.netloc (which includes port, e.g. localhost:8000) against base_domain (which has port stripped by get_base_domain()). This caused URLs like http://localhost:8000/page to be wrongly classified as external when the base domain is localhost, making the crawler stop after the first page when exclude_external_links=True.

The fix strips the port from parsed.netloc before comparison, consistent with how get_base_domain() handles ports.

Fixes #1503

List of files changed and why

• crawl4ai/utils.py — Strip port from URL netloc in is_external_url() before domain comparison

How Has This Been Tested?

Verified locally with test cases:

• http://localhost:8000/page with base localhost → correctly returns internal
• http://localhost:8000/page with base localhost:8000 → correctly returns internal
• Standard external/internal URL comparisons continue to work

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