feature: Outbox Relay and Kafka Pipeline

VigilCareClinicalAPI/Services/ObservationService.cs

@@ -116,7 +116,7 @@ public class ObservationService : IObservationService
                     severity = alert.Severity.ToDbString(),
                     triggeredAt = alert.TriggeredAt,
                     partitionKey = encounterId.ToString()
-                }));
+                }, encounterId.ToString()));
             }
 
             // Step 7 — outbox event for the observation (always; Kafka consumer handles warnings)
@@ -131,7 +131,7 @@ public class ObservationService : IObservationService
                 source = req.Source.ToDbString(),
                 recordedAt = req.RecordedAt,
                 partitionKey = encounterId.ToString()
-            }));
+            }, encounterId.ToString()));
 
             // Step 8 — COMMIT
             await _db.SaveChangesAsync();
@@ -202,11 +202,12 @@ public class ObservationService : IObservationService
         return $"{req.ObservationCode} value {req.Value} {req.Unit} is above critical high of {t.CriticalHigh} {req.Unit}.";
     }
 
-    private static OutboxEvent BuildOutboxEvent(string topic, object payload) => new()
+    private static OutboxEvent BuildOutboxEvent(string topic, object payload, string partitionKey) => new()
     {
         Id = Guid.NewGuid(),
         Topic = topic,
         Payload = JsonSerializer.Serialize(payload),
+        PartitionKey = partitionKey,
         CreatedAt = DateTimeOffset.UtcNow
     };