feat: add pull request template

- Add comprehensive PR template with bullet-point summary format
- Include checkboxes for common change types
- Provide section for related issues

Author: hrntknr

.github/pull_request_template.md

@@ -0,0 +1,19 @@
+## Summary
+
+- 
+- 
+- 
+
+## Type of Change
+
+- [ ] Bug fix (non-breaking change which fixes an issue)
+- [ ] New feature (non-breaking change which adds functionality)
+- [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
+- [ ] Documentation update
+- [ ] Refactoring (no functional changes)
+- [ ] Performance improvement
+- [ ] CI/CD change
+
+## Related Issues
+
+Closes #(issue number)