Standardize license headers in Python files

[pderrenger]

This PR updates all Python file headers to use a standardized license format. 🔄

Changes:

• 📝 Standardized header: # Ultralytics 🚀 AGPL-3.0 License - https://ultralytics.com/license
• 🧹 Ensures consistent spacing after headers
• 🔍 Applies to all Python files except those in venv

Learn more about Ultralytics licensing 📚

🛠️ PR Summary

_{Made with ❤️ by Ultralytics Actions}

🌟 Summary

Added the Ultralytics AGPL-3.0 license header across the repository for better transparency and legal clarity. 🚀

📊 Key Changes

• Added Ultralytics AGPL-3.0 license header to all major source files, including detect.py, train.py, models.py, and utility scripts in the utils and scoring directories.
• Minor fix to error message formatting in scoring/evaluation.py.

🎯 Purpose & Impact

• 🛡️ Ensures licensing clarity: Clearly states and enforces the AGPL-3.0 license across all files for proper usage and compliance.
• ✅ Improves uniformity: All files now include consistent licensing info, reducing ambiguity for external contributors and users.
• 🖐️ No functional impact: Purely informational and compliance-related update; no changes to the code logic or performance.

[UltralyticsAssistant]

👋 Hello @pderrenger, thank you for submitting an ultralytics/xview-yolov3 🚀 PR! To ensure a seamless integration of your work, please review the following checklist:

• ✅ Define a Purpose: Clearly explain the purpose of your fix or feature in your PR description, and link to any relevant issues. Ensure your commit messages are clear, concise, and adhere to the project's conventions.
• ✅ Synchronize with Source: Confirm your PR is synchronized with the ultralytics/xview-yolov3 main branch. If it's behind, update it by clicking the 'Update branch' button or by running git pull and git merge main locally.
• ✅ Ensure CI Checks Pass: Verify all Ultralytics Continuous Integration (CI) checks are passing. If any checks fail, please address the issues.
• ✅ Update Documentation: Update the relevant documentation for any new or modified features.
• ✅ Add Tests: If applicable, include or update tests to cover your changes, and confirm that all tests are passing.
• ✅ Sign the CLA: Please ensure you have signed our Contributor License Agreement if this is your first Ultralytics PR by writing "I have read the CLA Document and I sign the CLA" in a new message.
• ✅ Minimize Changes: Limit your changes to the minimum necessary for your bug fix or feature addition. "It is not daily increase but daily decrease, hack away the unessential. The closer to the source, the less wastage there is." — Bruce Lee

For more guidance, please refer to our Contributing Guide. Don’t hesitate to leave a comment if you have any questions. Thank you for contributing to Ultralytics! 🚀

This is an automated response to help expedite your PR review process. An Ultralytics engineer will review your changes shortly. 🎉

[UltralyticsAssistant]

The PR is merged! 🎉 Huge thanks to @pderrenger for leading the effort and @glenn-jocher for the support on this crucial update. Adding the AGPL-3.0 license headers across the entire repo is not just about compliance—it's about giving clarity and transparency to a fast-growing community. 🛡️🚀

As Marcus Aurelius once said, "What we do now echoes in eternity." Your contributions ensure that Ultralytics builds on a foundation of openness and integrity, echoing through every future innovation. Thank you for making a difference! ❤️