meta: add PR template

Adds pull request template with summary, changes checklist, and Closes # reference for linked issues.

Author: mod-lr

.github/PULL_REQUEST_TEMPLATE.md

@@ -0,0 +1,10 @@
+## Summary
+Describe the change and why it’s needed.
+
+## Linked Issue
+Closes #<issue-number>
+
+## Checklist
+- [ ] Tests/Checks pass locally
+- [ ] Changelog updated (if user-facing change)
+- [ ] Docs/README updated (if needed)