Refactored checkStatus() to delegate to NotificationStatusChecker service.
Changes:
- Added statusChecker service instance to plugin
- Initialize statusChecker in load() method
- Replaced 53 lines of status checking logic with 3-line delegation
- checkStatus() now calls NotificationStatusChecker.getComprehensiveStatus()
This is the first method in Batch A (pure delegation, read-only).
Verification:
- Service method exists and returns JSObject ✅
- Error handling preserved ✅
- No behavior change (delegation only) ✅
Reduction: ~50 lines removed from plugin class
