perf(test): replace DirtiesContext(AFTER_EACH_TEST_METHOD) with @Transactional

4 integration test classes were restarting the full Spring context (and a new
Postgres Testcontainer, ~75s each) after every test method — 10 unnecessary
container startups adding ~12 minutes to CI. Fixed by:

- PersonServiceIntegrationTest, DocumentSearchPagedIntegrationTest,
  GeschichteServiceIntegrationTest: swap to @Transactional so each test
  rolls back instead of destroying the context.
- AuditServiceIntegrationTest: cannot use @Transactional (logAfterCommit
  hooks into AFTER_COMMIT which requires a real commit); reset state with
  @BeforeEach deleteAll() instead.

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

backend/src/test/java/org/raddatz/familienarchiv/audit/AuditServiceIntegrationTest.java

@@ -1,11 +1,11 @@
 package org.raddatz.familienarchiv.audit;
 
+import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 import org.raddatz.familienarchiv.PostgresContainerConfig;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.test.context.SpringBootTest;
 import org.springframework.context.annotation.Import;
-import org.springframework.test.annotation.DirtiesContext;
 import org.springframework.test.context.ActiveProfiles;
 import org.springframework.test.context.bean.override.mockito.MockitoBean;
 import org.springframework.transaction.support.TransactionTemplate;
@@ -18,7 +18,6 @@ import static org.awaitility.Awaitility.await;
 @SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.NONE)
 @ActiveProfiles("test")
 @Import(PostgresContainerConfig.class)
-@DirtiesContext(classMode = DirtiesContext.ClassMode.AFTER_EACH_TEST_METHOD)
 class AuditServiceIntegrationTest {
 
     @MockitoBean S3Client s3Client;
@@ -26,6 +25,11 @@ class AuditServiceIntegrationTest {
     @Autowired AuditLogRepository auditLogRepository;
     @Autowired TransactionTemplate transactionTemplate;
 
+    @BeforeEach
+    void resetAuditLog() {
+        auditLogRepository.deleteAll();
+    }
+
     @Test
     void logAfterCommit_writes_ANNOTATION_CREATED_row_after_transaction_commits() {
         transactionTemplate.execute(status -> {

backend/src/test/java/org/raddatz/familienarchiv/document/DocumentSearchPagedIntegrationTest.java

@@ -12,9 +12,9 @@ import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.test.context.SpringBootTest;
 import org.springframework.context.annotation.Import;
 import org.springframework.data.domain.PageRequest;
-import org.springframework.test.annotation.DirtiesContext;
 import org.springframework.test.context.ActiveProfiles;
 import org.springframework.test.context.bean.override.mockito.MockitoBean;
+import org.springframework.transaction.annotation.Transactional;
 import software.amazon.awssdk.services.s3.S3Client;
 
 import java.time.LocalDate;
@@ -33,7 +33,7 @@ import static org.assertj.core.api.Assertions.assertThat;
 @SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.NONE)
 @ActiveProfiles("test")
 @Import(PostgresContainerConfig.class)
-@DirtiesContext(classMode = DirtiesContext.ClassMode.AFTER_EACH_TEST_METHOD)
+@Transactional
 class DocumentSearchPagedIntegrationTest {
 
     private static final int FIXTURE_SIZE = 120;

backend/src/test/java/org/raddatz/familienarchiv/geschichte/GeschichteServiceIntegrationTest.java

@@ -19,9 +19,9 @@ import org.springframework.context.annotation.Import;
 import org.springframework.security.authentication.UsernamePasswordAuthenticationToken;
 import org.springframework.security.core.authority.SimpleGrantedAuthority;
 import org.springframework.security.core.context.SecurityContextHolder;
-import org.springframework.test.annotation.DirtiesContext;
 import org.springframework.test.context.ActiveProfiles;
 import org.springframework.test.context.bean.override.mockito.MockitoBean;
+import org.springframework.transaction.annotation.Transactional;
 import software.amazon.awssdk.services.s3.S3Client;
 
 import java.util.List;
@@ -32,7 +32,7 @@ import static org.assertj.core.api.Assertions.assertThat;
 @SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.NONE)
 @ActiveProfiles("test")
 @Import(PostgresContainerConfig.class)
-@DirtiesContext(classMode = DirtiesContext.ClassMode.AFTER_EACH_TEST_METHOD)
+@Transactional
 class GeschichteServiceIntegrationTest {
 
     @MockitoBean

backend/src/test/java/org/raddatz/familienarchiv/person/PersonServiceIntegrationTest.java

@@ -8,9 +8,9 @@ import org.raddatz.familienarchiv.person.PersonRepository;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.test.context.SpringBootTest;
 import org.springframework.context.annotation.Import;
-import org.springframework.test.annotation.DirtiesContext;
 import org.springframework.test.context.ActiveProfiles;
 import org.springframework.test.context.bean.override.mockito.MockitoBean;
+import org.springframework.transaction.annotation.Transactional;
 import software.amazon.awssdk.services.s3.S3Client;
 
 import static org.assertj.core.api.Assertions.assertThat;
@@ -18,7 +18,7 @@ import static org.assertj.core.api.Assertions.assertThat;
 @SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.NONE)
 @ActiveProfiles("test")
 @Import(PostgresContainerConfig.class)
-@DirtiesContext(classMode = DirtiesContext.ClassMode.AFTER_EACH_TEST_METHOD)
+@Transactional
 class PersonServiceIntegrationTest {
 
     @MockitoBean S3Client s3Client;