merge: external-system retry policy end-to-end (register row 27) — MaxRetries/RetryDelay now travel artifact→gRPC→site schema→S&F enqueue, CLI --max-retries/--retry-delay-seconds, ArtifactDiff compares them

src/ZB.MOM.WW.ScadaBridge.Communication/Grpc/SiteCommandDtoMapper.cs

@@ -506,7 +506,9 @@ public static class SiteCommandDtoMapper
             AuthType = artifact.AuthType,
             AuthConfiguration = OrEmpty(artifact.AuthConfiguration),
             MethodDefinitionsJson = OrEmpty(artifact.MethodDefinitionsJson),
-            TimeoutSeconds = artifact.TimeoutSeconds
+            TimeoutSeconds = artifact.TimeoutSeconds,
+            MaxRetries = artifact.MaxRetries,
+            RetryDelay = Duration.FromTimeSpan(artifact.RetryDelay)
         };
     }
 
@@ -523,7 +525,9 @@ public static class SiteCommandDtoMapper
             dto.AuthType,
             NullIfEmpty(dto.AuthConfiguration),
             NullIfEmpty(dto.MethodDefinitionsJson),
-            dto.TimeoutSeconds);
+            dto.TimeoutSeconds,
+            dto.MaxRetries,
+            dto.RetryDelay?.ToTimeSpan() ?? TimeSpan.Zero);
     }
 
     /// <summary>Projects a <see cref="DatabaseConnectionArtifact"/> onto the wire.</summary>

src/ZB.MOM.WW.ScadaBridge.Communication/Protos/site_command.proto

@@ -224,6 +224,11 @@ message ExternalSystemArtifactDto {
   string auth_configuration = 4;        // empty string represents null
   string method_definitions_json = 5;   // empty string represents null
   int32 timeout_seconds = 6;
+  // Store-and-Forward retry policy for this system's cached calls. Additive (fields 7-8);
+  // a pre-existing site decodes them as 0/absent, which is exactly the "unset" value that
+  // makes the engine defaults apply — i.e. the old behaviour.
+  int32 max_retries = 7;
+  google.protobuf.Duration retry_delay = 8;
 }
 
 message DatabaseConnectionArtifactDto {