Verify signing test

[Ily17as]

Goal

Complete Lab 1: demonstrate SSH commit signing and add a standardized PR template.

Changes

• Added submission1.md with a summary of the benefits of signing commits:
  authenticity, integrity, accountability, security in collaboration, and compliance.
• Configured and tested SSH commit signing (commits show as "Verified").
• Added .github/pull_request_template.md on the main branch for consistent PRs.

Testing

• Confirmed submission1.md exists in the feature/lab1 branch.
• Verified signed commits on GitHub show the green "Verified" badge.
• Opened this PR and confirmed the template auto-filled the description.

Checklist

• PR has a clear, descriptive title
• Documentation / README updated if needed
• No secrets or large temporary files included