feat: add configurable platform appearance (#385)

backend/cmd/server/main.go

@@ -113,6 +113,7 @@ func run(ctx context.Context) error {
 	registerSystemStatusRoutes(api, status)
 	handler.RegisterOAuthCallbackRoutes(r, svc)
 	handler.RegisterAuthRoutes(api, svc)
+	handler.RegisterAppearanceRoutes(api, svc)
 	handler.RegisterFeatureAvailabilityRoutes(api, svc)
 	handler.RegisterResponseInterceptionRoutes(api, svc)
 	handler.RegisterAdminRoutes(api, svc)