Add comprehensive tests for Security Dashboard functionality

- Implement tests for Security Dashboard card status verification (SD-01 to SD-10) to ensure correct display of security statuses and toggle functionality.
- Create error handling tests (EH-01 to EH-10) to validate error messages on API failures, toast notifications on mutation errors, and optimistic update rollback.
- Develop loading overlay tests (LS-01 to LS-10) to verify the appearance of loading indicators during operations and ensure interactions are blocked appropriately.

docs/plans/cerberus_integration_testing_plan.md

@@ -3,7 +3,7 @@
 **Version:** 1.0
 **Date:** 2025-12-12
 **Issue:** #319
-**Status:** 🔵 READY FOR TESTING
+**Status:** ✅ COMPLETE
 
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