Implement status aggregation with notification batching

shared/src/metrics.rs

@@ -83,6 +83,7 @@ impl MetricValue {
 #[derive(Debug, Clone, Copy, Serialize, Deserialize, PartialEq, Eq, PartialOrd, Ord)]
 pub enum Status {
     Ok,
+    Pending,
     Warning,
     Critical,
     Unknown,
@@ -179,6 +180,16 @@ impl HysteresisThresholds {
                     Status::Ok
                 }
             }
+            Status::Pending => {
+                // Service transitioning, use normal thresholds like first measurement
+                if value >= self.critical_high {
+                    Status::Critical
+                } else if value >= self.warning_high {
+                    Status::Warning
+                } else {
+                    Status::Ok
+                }
+            }
         }
     }
 }