Fix memory exhaustion and implement streaming for Wayback Machine URLs

[AliHz1337]

Problem

The current Wayback Machine URL fetching implementation suffers from critical memory management issues that cause application crashes when processing domains with large archives:

Issues Identified:

• Memory exhaustion: Collecting all URLs in memory before returning causes OOM kills
• Process crashes: Large enterprise domains consistently crash the application
• Poor scalability: Memory usage grows linearly with archive size
• Blocking behavior: Application hangs for minutes before eventual crash

Reproduction Case:

Testing with indeed.com (a domain with extensive web archives):

./waybackurls indeed.com
# Result: Application hangs → Memory usage grows → OOM kill after ~15 minutes
# No URLs output during the hang period