ci: add pull request template

.github/pull_request_template.md

@@ -0,0 +1,37 @@
+## What does this PR do?
+
+<!-- Brief description of the change and why it's needed. -->
+
+## PR title
+
+<!-- Your PR title must follow Conventional Commits. It becomes the squash-merge commit message and is parsed by release-please.
+
+Valid prefixes: feat, fix, docs, ci, build, chore, perf, refactor, revert, style, test
+Examples:
+  feat: add multi-AZ failover support
+  fix: prevent duplicate EIP attachment on concurrent events
+  docs: update architecture diagrams
+  feat!: rename vpc_id to vpc_identifier (BREAKING CHANGE)
+
+Release impact:
+  feat: → minor version bump
+  fix:  → patch version bump
+  feat! / BREAKING CHANGE: → major version bump
+  Everything else → no release
+-->
+
+## Checklist
+
+- [ ] PR title follows [Conventional Commits](https://www.conventionalcommits.org/) format
+- [ ] Changes are tested (unit tests, manual verification, or integration tests as appropriate)
+- [ ] Documentation updated if user-facing behavior changed
+
+## Integration tests
+
+<!-- If your change touches Terraform modules, Lambda code, or NAT instance behavior, add the `integration-test` label to this PR to run the full AWS integration suite. This requires environment approval from a code owner.
+
+For AMI changes, add the `nat-images` label instead. -->
+
+- [ ] Not needed — docs, CI, or non-infra change
+- [ ] Needed — `integration-test` label added
+- [ ] AMI change — `nat-images` label added