Devlog #3 Core Checker Refactor, Batch Processing, and First PR Merge

Today, I finalized the core URL checking logic and batch processing implementation! I added proper input sanitization, mapped network errors to user-friendly messages, cleaned up temporary interactive test code, and successfully merged Pull Request #6 into main using Squash and Merge.

My Next Target 🎯

• Accept website URLs as command-line arguments
• Connect the CLI to the core checker
• Display availability, HTTP status codes, and response times
• Handle invalid input and request failures
• Provide basic usage information and appropriate exit codes