feat(healthcheck): add retries before notifying (default: 3 times)

- Introduced NotifyFunc type for customizable notification handling in tests.
- Added Retries field to HealthCheckConfig for controlling notification thresholds.
- Implemented tests for notification behavior under various health check scenarios.

internal/utils/atomic/std.go

@@ -3,3 +3,5 @@ package atomic
 import "sync/atomic"
 
 type Bool = atomic.Bool
+type Int32 = atomic.Int32
+type Int64 = atomic.Int64