feat(m9/T24a): guarded move-data-connection-between-sites command + handler

src/ZB.MOM.WW.ScadaBridge.ConfigurationDatabase/Repositories/SiteRepository.cs

@@ -125,13 +125,37 @@ public class SiteRepository : ISiteRepository
         return Task.CompletedTask;
     }
 
-    // --- Instances (for deletion constraint checks) ---
+    // --- Instances (for deletion / move constraint checks) ---
 
     /// <inheritdoc />
     public async Task<IReadOnlyList<Instance>> GetInstancesBySiteIdAsync(int siteId, CancellationToken cancellationToken = default)
     {
         return await _dbContext.Instances
             .Where(i => i.SiteId == siteId)
+            .Include(i => i.ConnectionBindings)
+            .Include(i => i.NativeAlarmSourceOverrides)
+            .AsSplitQuery()
+            .ToListAsync(cancellationToken);
+    }
+
+    /// <inheritdoc />
+    public async Task<IReadOnlyList<Instance>> GetInstancesReferencingDataConnectionAsync(int dataConnectionId, CancellationToken cancellationToken = default)
+    {
+        // The distinct instance ids whose bindings reference the connection.
+        // Bindings are not exposed via their own DbSet on ISiteRepository, so
+        // resolve them through the InstanceConnectionBindings set, then load the
+        // owning instances (cheap; the blocker list is expected to be tiny).
+        var instanceIds = await _dbContext.InstanceConnectionBindings
+            .Where(b => b.DataConnectionId == dataConnectionId)
+            .Select(b => b.InstanceId)
+            .Distinct()
+            .ToListAsync(cancellationToken);
+
+        if (instanceIds.Count == 0)
+            return Array.Empty<Instance>();
+
+        return await _dbContext.Instances
+            .Where(i => instanceIds.Contains(i.Id))
             .ToListAsync(cancellationToken);
     }