fix: add lenient mock strictness to AgentStatusServiceTest

The serverApiClient.isAvailable() stubbing in setUp() is unused by
the observability test, causing UnnecessaryStubbingException in CI.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/test/java/net/siegeln/cameleer/saas/observability/AgentStatusServiceTest.java

@@ -10,6 +10,8 @@ import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.extension.ExtendWith;
 import org.mockito.Mock;
 import org.mockito.junit.jupiter.MockitoExtension;
+import org.mockito.junit.jupiter.MockitoSettings;
+import org.mockito.quality.Strictness;
 
 import java.util.Optional;
 import java.util.UUID;
@@ -19,6 +21,7 @@ import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.Mockito.*;
 
 @ExtendWith(MockitoExtension.class)
+@MockitoSettings(strictness = Strictness.LENIENT)
 class AgentStatusServiceTest {
 
     @Mock private AppRepository appRepository;