docs: add pull request template

Add .github/PULL_REQUEST_TEMPLATE.md to guide contributors on how to write good PR descriptions. Addresses issue #356.

Author: Typo Fix Bot

.github/PULL_REQUEST_TEMPLATE.md

@@ -0,0 +1,15 @@
+## What does this PR do?
+Short description of the changes.
+
+## Motivation
+Why is this change needed? What problem does it solve?
+
+## How to test
+Steps to verify the change works correctly.
+
+## Checklist
+- [ ] I followed the contributing guidelines
+- [ ] Tests added or updated (if applicable)
+- [ ] Documentation updated (if applicable)
+- [ ] Code compiles without errors
+- [ ] No sensitive data committed