Add pull request template with checklist for contributors

[kmuwanga83]

📌 Problem

Pull requests lack consistency and often miss important information.

🎯 Objective

Standardize pull requests using a template.

✅ Tasks

• Create .github/pull_request_template.md
• Include checklist:
  • linked issue
  • tests added
  • documentation updated
  • screenshots (if UI)

🧪 Acceptance Criteria

• PR template appears automatically
• Contributors follow checklist
• Reviews become easier and faster

💡 Suggested Labels

community, maintenance