chore: add GitHub pull request template

Author: Pavel Siska

.github/PULL_REQUEST_TEMPLATE/pull_request_template.md

@@ -0,0 +1,21 @@
+### Summary
+
+_Provide an overview..._
+
+### Details
+
+_Add more context to describe the changes..._
+
+---
+
+### ✅ Checks
+
+- [ ] Relevant documentation was updated (if needed)
+- [ ] CI pipeline passes (build, tests, lint, static analysis)
+- [ ] New code follows clang-tidy rules
+- [ ] The change is clearly related to a specific issue / requirement
+- [ ] Documentation (e.g. Doxygen) is updated if needed
+- [ ] The PR is rebased on the latest `master`
+- [ ] No unrelated changes are included
+
+---