feature: Outbox Relay and Kafka Pipeline

VigilCareClinicalAPI/Services/EncounterService.cs

@@ -1,3 +1,4 @@
+using System.Text.Json;
 using Microsoft.EntityFrameworkCore;
 
 public class EncounterService : IEncounterService
@@ -41,11 +42,29 @@ public class EncounterService : IEncounterService
             throw new ConflictException(
                 $"Transition to '{targetStatus}' is not permitted from the current status.",
                 "ILLEGAL_STATUS_TRANSITION");
-
+        
+        var previousStatus = encounter.Status;
         encounter.Status = targetStatus;
+
         if (targetStatus == EncounterStatus.Discharged)
             encounter.DischargedAt = DateTimeOffset.UtcNow;
 
+        _db.OutboxEvents.Add(new OutboxEvent
+        {
+            Id = Guid.NewGuid(),
+            Topic = "encounter.status.changed",
+            Payload = JsonSerializer.Serialize(new
+            {
+                encounterId,
+                patientId = encounter.PatientId,
+                previousStatus = previousStatus.ToDbString(),
+                newStatus = targetStatus.ToDbString(),
+                changedAt = DateTimeOffset.UtcNow
+            }),
+            PartitionKey = encounterId.ToString(),
+            CreatedAt = DateTimeOffset.UtcNow
+        });
+
         await _db.SaveChangesAsync();
         return new EncounterStatusTransitionResult(encounterId, targetStatus);
     }