feat: implement multi-tenancy support across knowledge services and normalize TenantId to string type.

src/NexusReader.Maui/MauiProgram.cs

@@ -49,6 +49,10 @@ public static class MauiProgram
 			builder.Services.AddScoped<IIdentityService, IdentityService>();
 			
 			builder.Services.AddApplication();
+			
+			builder.Services.AddMediatR(cfg => cfg.RegisterServicesFromAssemblies(
+				NexusReader.Application.DependencyInjection.Assembly
+			));
 
 			return builder.Build();
 		}