feat(audit): emit USER_CREATED when admin creates a new user

Adds USER_CREATED, USER_DELETED, GROUP_MEMBERSHIP_CHANGED to AuditKind.
Injects AuditService into UserService; changes createUserOrUpdate to
accept actorId and emits logAfterCommit(USER_CREATED) only on the
new-user branch. Updates UserController to resolve and pass actorId.

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

backend/src/main/java/org/raddatz/familienarchiv/audit/AuditKind.java

@@ -26,7 +26,16 @@ public enum AuditKind {
     COMMENT_ADDED,
 
     /** Payload: {@code {"commentId": "uuid", "mentionedUserId": "uuid"}} */
-    MENTION_CREATED;
+    MENTION_CREATED,
+
+    /** Payload: {@code {"userId": "uuid", "email": "addr"}} */
+    USER_CREATED,
+
+    /** Payload: {@code {"userId": "uuid", "email": "addr"}} */
+    USER_DELETED,
+
+    /** Payload: {@code {"userId": "uuid", "email": "addr", "addedGroups": ["Admin"], "removedGroups": []}} */
+    GROUP_MEMBERSHIP_CHANGED;
 
     public static final Set<AuditKind> ROLLUP_ELIGIBLE = Set.of(
             TEXT_SAVED, FILE_UPLOADED, ANNOTATION_CREATED,

backend/src/main/java/org/raddatz/familienarchiv/controller/UserController.java

@@ -78,8 +78,10 @@ public class UserController {
 
     @PostMapping("/users")
     @RequirePermission(Permission.ADMIN_USER)
-    public ResponseEntity<AppUser> createUser(@Valid @RequestBody CreateUserRequest request) {
+    public ResponseEntity<AppUser> createUser(Authentication authentication,
-        return ResponseEntity.ok(userService.createUserOrUpdate(request));
+                                              @Valid @RequestBody CreateUserRequest request) {
+        AppUser actor = userService.findByEmail(authentication.getName());
+        return ResponseEntity.ok(userService.createUserOrUpdate(actor.getId(), request));
     }
 
     @PutMapping("/users/{id}")

backend/src/main/java/org/raddatz/familienarchiv/service/UserService.java

@@ -3,6 +3,8 @@ package org.raddatz.familienarchiv.service;
 import lombok.RequiredArgsConstructor;
 import lombok.extern.slf4j.Slf4j;
 
+import org.raddatz.familienarchiv.audit.AuditKind;
+import org.raddatz.familienarchiv.audit.AuditService;
 import org.raddatz.familienarchiv.dto.AdminUpdateUserRequest;
 import org.raddatz.familienarchiv.dto.ChangePasswordDTO;
 import org.raddatz.familienarchiv.dto.CreateUserRequest;
@@ -21,6 +23,7 @@ import org.springframework.transaction.annotation.Transactional;
 import java.util.Collection;
 import java.util.HashSet;
 import java.util.List;
+import java.util.Map;
 import java.util.Optional;
 import java.util.Set;
 import java.util.UUID;
@@ -33,9 +36,10 @@ public class UserService {
     private final AppUserRepository userRepository;
     private final UserGroupRepository groupRepository;
     private final PasswordEncoder passwordEncoder;
+    private final AuditService auditService;
 
     @Transactional
-    public AppUser createUserOrUpdate(CreateUserRequest request) {
+    public AppUser createUserOrUpdate(UUID actorId, CreateUserRequest request) {
         log.info("Creating or updating user: {}", request.getEmail());
 
         Set<UserGroup> groups = new HashSet<>();
@@ -45,10 +49,12 @@ public class UserService {
 
         Optional<AppUser> existingUser = userRepository.findByEmail(request.getEmail());
         AppUser user;
+        boolean isNew;
 
         if (existingUser.isPresent()) {
             log.info("User exists, updating: {}", request.getEmail());
             user = existingUser.get().updateFromRequest(request, passwordEncoder, groups);
+            isNew = false;
         } else {
             log.info("Creating new user: {}", request.getEmail());
             user = AppUser.builder()
@@ -61,9 +67,15 @@ public class UserService {
                     .contact(request.getContact())
                     .enabled(true)
                     .build();
+            isNew = true;
         }
 
-        return userRepository.save(user);
+        AppUser saved = userRepository.save(user);
+        if (isNew) {
+            auditService.logAfterCommit(AuditKind.USER_CREATED, actorId, null,
+                    Map.of("userId", saved.getId().toString(), "email", saved.getEmail()));
+        }
+        return saved;
     }
 
     @Transactional

backend/src/test/java/org/raddatz/familienarchiv/service/UserServiceTest.java

@@ -2,9 +2,12 @@ package org.raddatz.familienarchiv.service;
 
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.extension.ExtendWith;
+import org.mockito.ArgumentCaptor;
 import org.mockito.InjectMocks;
 import org.mockito.Mock;
 import org.mockito.junit.jupiter.MockitoExtension;
+import org.raddatz.familienarchiv.audit.AuditKind;
+import org.raddatz.familienarchiv.audit.AuditService;
 import org.raddatz.familienarchiv.dto.AdminUpdateUserRequest;
 import org.raddatz.familienarchiv.dto.ChangePasswordDTO;
 import org.raddatz.familienarchiv.dto.CreateUserRequest;
@@ -34,6 +37,7 @@ class UserServiceTest {
     @Mock AppUserRepository userRepository;
     @Mock UserGroupRepository groupRepository;
     @Mock PasswordEncoder passwordEncoder;
+    @Mock AuditService auditService;
     @InjectMocks UserService userService;
 
     // ─── findByEmail ──────────────────────────────────────────────────────────
@@ -90,7 +94,7 @@ class UserServiceTest {
         AppUser saved = AppUser.builder().id(UUID.randomUUID()).email("new@example.com").build();
         when(userRepository.save(any())).thenReturn(saved);
 
-        AppUser result = userService.createUserOrUpdate(req);
+        AppUser result = userService.createUserOrUpdate(UUID.randomUUID(), req);
 
         assertThat(result).isEqualTo(saved);
         verify(userRepository).save(any());
@@ -108,7 +112,7 @@ class UserServiceTest {
         when(passwordEncoder.encode(any())).thenReturn("encoded");
         when(userRepository.save(any())).thenReturn(existing);
 
-        userService.createUserOrUpdate(req);
+        userService.createUserOrUpdate(UUID.randomUUID(), req);
 
         verify(userRepository, times(1)).save(existing);
     }
@@ -313,7 +317,7 @@ class UserServiceTest {
         AppUser saved = AppUser.builder().id(UUID.randomUUID()).email("u@example.com").build();
         when(userRepository.save(any())).thenReturn(saved);
 
-        AppUser result = userService.createUserOrUpdate(req);
+        AppUser result = userService.createUserOrUpdate(UUID.randomUUID(), req);
 
         assertThat(result).isEqualTo(saved);
         verify(groupRepository).findAllById(List.of(group.getId()));
@@ -497,7 +501,7 @@ class UserServiceTest {
         AppUser saved = AppUser.builder().id(UUID.randomUUID()).email("u@example.com").build();
         when(userRepository.save(any())).thenReturn(saved);
 
-        userService.createUserOrUpdate(req);
+        userService.createUserOrUpdate(UUID.randomUUID(), req);
 
         verify(groupRepository, never()).findAllById(any());
     }
@@ -640,7 +644,7 @@ class UserServiceTest {
         AppUser saved = AppUser.builder().id(UUID.randomUUID()).email("ng@example.com").build();
         when(userRepository.save(any())).thenReturn(saved);
 
-        userService.createUserOrUpdate(req);
+        userService.createUserOrUpdate(UUID.randomUUID(), req);
 
         verify(groupRepository, never()).findAllById(any());
     }
@@ -699,6 +703,52 @@ class UserServiceTest {
         assertThat(result).containsExactly(g);
     }
 
+    // ─── audit: USER_CREATED ──────────────────────────────────────────────────
+
+    @Test
+    void createUserOrUpdate_logsUserCreated_whenUserIsNew() {
+        UUID actorId = UUID.randomUUID();
+        CreateUserRequest req = new CreateUserRequest();
+        req.setEmail("new@example.com");
+        req.setInitialPassword("secret");
+        req.setGroupIds(List.of());
+
+        when(userRepository.findByEmail("new@example.com")).thenReturn(Optional.empty());
+        when(passwordEncoder.encode("secret")).thenReturn("encoded");
+        AppUser saved = AppUser.builder().id(UUID.randomUUID()).email("new@example.com").build();
+        when(userRepository.save(any())).thenReturn(saved);
+
+        userService.createUserOrUpdate(actorId, req);
+
+        @SuppressWarnings("unchecked")
+        ArgumentCaptor<java.util.Map<String, Object>> payloadCaptor = ArgumentCaptor.forClass(java.util.Map.class);
+        verify(auditService).logAfterCommit(
+                org.mockito.ArgumentMatchers.eq(AuditKind.USER_CREATED),
+                org.mockito.ArgumentMatchers.eq(actorId),
+                org.mockito.ArgumentMatchers.isNull(),
+                payloadCaptor.capture());
+        assertThat(payloadCaptor.getValue()).containsKey("userId");
+        assertThat(payloadCaptor.getValue()).containsEntry("email", "new@example.com");
+    }
+
+    @Test
+    void createUserOrUpdate_doesNotLogUserCreated_whenUserAlreadyExists() {
+        UUID actorId = UUID.randomUUID();
+        CreateUserRequest req = new CreateUserRequest();
+        req.setEmail("existing@example.com");
+        req.setInitialPassword("pass");
+        req.setGroupIds(List.of());
+
+        AppUser existing = AppUser.builder().id(UUID.randomUUID()).email("existing@example.com").build();
+        when(userRepository.findByEmail("existing@example.com")).thenReturn(Optional.of(existing));
+        when(passwordEncoder.encode(any())).thenReturn("encoded");
+        when(userRepository.save(any())).thenReturn(existing);
+
+        userService.createUserOrUpdate(actorId, req);
+
+        verify(auditService, never()).logAfterCommit(any(), any(), any(), any());
+    }
+
     // ─── createGroup ──────────────────────────────────────────────────────────
 
     @Test