Changes

PR #1392 by ksylvan: chore: enhance argument validation in code_helper tool

• Refactor: streamline code_helper CLI interface and require explicit instructions
• Require exactly two arguments: directory and instructions
• Remove dedicated help flag, use flag.Usage instead
• Improve directory validation to check if it's a directory
• Inline pattern parsing, removing separate function

PR #1390 by PatrickCLee: docs: improve README link

• Fix broken what-and-why link reference