docs(developer-guide): fix undefined variable in example and improve …

[praharsh777]

Description

This PR introduces small documentation improvements to docs/developer-guide.md.

While reviewing the developer guide, I noticed that a Python example in the Code Style section referenced an undefined variable (ticket_id) in the return statement. Since this variable was not defined anywhere in the function, it could confuse developers reading the example. The example was updated to return a defined value using customer_id instead.

Additionally, the Codex CLI example block was updated to include a text language tag for better Markdown formatting and consistency with other code blocks in the documentation.

These are documentation-only changes and do not modify any framework functionality.

Type of Change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Refactoring (no functional changes)

Related Issues

N/A

Changes Made

• Fixed undefined variable (ticket_id) in the Python example in developer-guide.md
• Updated the return statement to use the defined variable customer_id
• Added text language tag to the Codex CLI example block for improved formatting

Testing

Documentation-only changes. No code execution or automated tests were required.

• Unit tests pass (cd core && pytest tests/)
• Lint passes (cd core && ruff check .)
• Manual testing performed

Checklist

• My code follows the project's style guidelines
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes