✨ feat: add development environment configuration and update sample data generation

[iShelar]

• Introduced a new development.env file for environment variable configuration.
• Updated README to reflect new task command for generating sample data.
• Added django:generate-sample-data task to Taskfile for easier sample data generation.
• Refactored factories in factories.py to use Wagtail factories and improved sample data generation logic in the management command.

[matrixise]

Thanks so much for addressing the feedback and refactoring the code back to proper factory-boy patterns! I really appreciate your responsiveness and the quality of the updates.

Moving forward, I should add some automated checks (pre-commit hooks, CI validations, etc.) to catch these kinds of issues earlier. That way, contributors won't need multiple review cycles just to get their contributions merged. It'll make the process smoother for everyone.