fix(e2e): activate e2e profile in dev mode and create reader user idempotently

- Add e2e to the dev Maven profile's spring.profiles.active so
  DataInitializer always runs when developing/testing locally
- Create the reader test user independently of the person-seed guard
  so it survives restarts where seed data already exists
- Set SPRING_PROFILES_ACTIVE=dev,e2e in docker-compose backend service

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/pom.xml

@@ -148,7 +148,7 @@
 				<activeByDefault>true</activeByDefault>
 			</activation>
 			<properties>
-				<spring.profiles.active>dev</spring.profiles.active>
+				<spring.profiles.active>dev,e2e</spring.profiles.active>
 			</properties>
 		</profile>
 		<profile>