- Add 'Checks' tab link to device navigation
- Display empty state when no checks configured
- Add tests for tab visibility and empty state
- Fix unused variable warnings in monitoring context
- Remove unused CheckResult alias and module attributes
- Add stub for legacy get_latency_data for backward compatibility
Tests: 2 new tests added, all passing
Following TDD: RED-GREEN cycle verified for each feature
Graham McIntire
07a6128877