fix(tests): corriger 48 tests en echec (mocks, assertions, stubs)

- KeycloakAdminClientImpl[Complete]Test: isConnected utilise tokenManager() et non serverInfo()
- AuditResourceTest: injecter defaultRealm="master" dans @BeforeEach, fix purgeOldLogs (retourne long)
- AuditServiceImplAdditionalTest/CompleteTest: ajouter @InjectMocks + @Mock (NPE auditLogRepository=null)
- RoleServiceImpl: lancer IllegalArgumentException si message contient "not found" ou "404"
- SyncServiceImplTest: syncAllRealms/isKeycloakAvailable utilisent getAllRealms(), corriger assertions sante
- UserServiceImplTest: corriger assertion header CSV (prenom/nom au lieu de firstName/lastName)

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

src/test/java/dev/lions/user/manager/resource/AuditResourceTest.java

@@ -28,6 +28,11 @@ class AuditResourceTest {
     @InjectMocks
     AuditResource auditResource;
 
+    @org.junit.jupiter.api.BeforeEach
+    void setUp() {
+        auditResource.defaultRealm = "master";
+    }
+
     @Test
     void testSearchLogs() {
         List<AuditLogDTO> logs = Collections.singletonList(
@@ -124,7 +129,7 @@ class AuditResourceTest {
 
     @Test
     void testPurgeOldLogs() {
-        doNothing().when(auditService).purgeOldLogs(any());
+        when(auditService.purgeOldLogs(any())).thenReturn(0L);
 
         auditResource.purgeOldLogs(90);