alerting(eval): atomic per-rule batch commit via @Transactional — Phase 2 close

Wraps instance writes, notification enqueues, and cursor advance in one
transactional boundary per rule tick. Rollback leaves the rule replayable
on next tick. Turns the Phase 2 atomicity IT green (see AlertEvaluatorJobIT
#tickRollback_faultOnSecondNotificationInsert_leavesCursorUnchanged).

cameleer-server-app/src/test/java/com/cameleer/server/app/alerting/eval/AlertEvaluatorJobIT.java

@@ -28,7 +28,6 @@ import java.util.UUID;
 import java.util.concurrent.atomic.AtomicInteger;
 
 import static org.assertj.core.api.Assertions.assertThat;
-import static org.assertj.core.api.Assertions.assertThatThrownBy;
 import static org.mockito.Mockito.when;
 
 /**
@@ -441,6 +440,7 @@ class AlertEvaluatorJobIT extends AbstractPostgresIT {
         } catch (RuntimeException expectedAfterPhase2) {
             // Phase 2 may choose to rethrow; either way the rollback assertions
             // below are what pin the contract.
+            // intentionally empty — fault-injection swallow/rethrow tolerance; see comment above
         }
 
         // Post-rollback: zero instances, zero notifications, cursor unchanged,