chore: initialize from backend template 0a6dd0e

.github/pull_request_template.md

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+## What changed and why
+
+<!-- Summarize the behavior, architecture boundary, or policy being changed. -->
+
+## Verification
+
+- [ ] I ran the focused test for each changed leaf.
+- [ ] I ran `cd src && ./gradlew check verifyPublicPathSnapshot verifyDependencyLocks`.
+- [ ] I did not add an unregistered production module dependency.
+- [ ] Dependency changes include refreshed `gradle.lockfile` files and a strict-lock verification.
+- [ ] Trivy suppressions include an owner-reviewed reason and an expiry within 90 days.
+- [ ] Any quarantined test is registered in `flaky-quarantine.yaml` with a reason, issue, and
+      `quarantined_since` date.
+- [ ] I documented checks that could not run and their remaining risk.
+
+## Compatibility and operations
+
+<!-- Note public API/config changes, migration needs, rollout/rollback impact, and external blockers. -->