Add GitHub Pull Request template (#563)

Author: Copilot

.github/PULL_REQUEST_TEMPLATE.md

@@ -0,0 +1,61 @@
+# Summary
+## What changed?
+-
+
+## Why is this change needed?
+-
+
+## Issues / work items
+- Resolves #
+- Related #
+
+---
+
+# Project checklist
+- [ ] Release notes are not required for the next release
+  - [ ] Otherwise: Notes added to `release_notes.md`
+- [ ] Backport is not required
+  - [ ] Otherwise: Backport tracked by issue/PR #issue_or_pr
+- [ ] All required tests have been added/updated (unit tests, E2E tests)
+- [ ] Breaking change?
+  - [ ] If yes:
+    - Impact:
+    - Migration guidance:
+---
+
+# AI-assisted code disclosure (required)
+## Was an AI tool used? (select one)
+- [ ] No
+- [ ] Yes, AI helped write parts of this PR (e.g., GitHub Copilot)
+- [ ] Yes, an AI agent generated most of this PR
+
+If AI was used:
+- Tool(s):
+- AI-assisted areas/files:
+- What you changed after AI output:
+
+AI verification (required if AI was used):
+- [ ] I understand the code and can explain it
+- [ ] I verified referenced APIs/types exist and are correct
+- [ ] I reviewed edge cases/failure paths (timeouts, retries, cancellation, exceptions)
+- [ ] I reviewed concurrency/async behavior
+- [ ] I checked for unintended breaking or behavior changes
+
+---
+
+# Testing
+## Automated tests
+- Result: Passed / Failed (link logs if failed)
+
+## Manual validation (only if runtime/behavior changed)
+- Environment (OS, .NET version, components):
+- Steps + observed results:
+  1.
+  2.
+  3.
+- Evidence (optional):
+
+---
+
+# Notes for reviewers
+- N/A