Improve test coverage and fix code quality issues in convert.py

[theanand108]

Description

This PR improves test coverage and code quality for convert.py.

Changes include:

• Increased test coverage (now ~87%)
• Added tests for command argument handling and execution flow
• Fixed flake8 issues (import order, trailing whitespace, formatting)
• Applied black formatting
• Ignored generated files (output.yaml)

No functional changes were made — only test quality and code style improvements.
Resolved or fixed issue: none

AI Tool Disclosure

• My contribution does not include any AI-generated content
• My contribution includes AI-generated content, as disclosed below:
  • AI Tools: ChatGPT
  • LLMs and versions: GPT-5.3
  • Prompts: Assisted with debugging tests, fixing lint issues, and improving code structure

Affirmation

• My code follows the CONTRIBUTING.md guidelines