feat: refine proxy export and toolbar layout

backend/internal/handler/admin/proxy_data_handler_test.go

@@ -75,6 +75,45 @@ func TestProxyExportDataRespectsFilters(t *testing.T) {
 	require.Equal(t, "https", resp.Data.Proxies[0].Protocol)
 }
 
+func TestProxyExportDataWithSelectedIDs(t *testing.T) {
+	router, adminSvc := setupProxyDataRouter()
+
+	adminSvc.proxies = []service.Proxy{
+		{
+			ID:       1,
+			Name:     "proxy-a",
+			Protocol: "http",
+			Host:     "127.0.0.1",
+			Port:     8080,
+			Username: "user",
+			Password: "pass",
+			Status:   service.StatusActive,
+		},
+		{
+			ID:       2,
+			Name:     "proxy-b",
+			Protocol: "https",
+			Host:     "10.0.0.2",
+			Port:     443,
+			Username: "u",
+			Password: "p",
+			Status:   service.StatusDisabled,
+		},
+	}
+
+	rec := httptest.NewRecorder()
+	req := httptest.NewRequest(http.MethodGet, "/api/v1/admin/proxies/data?ids=2", nil)
+	router.ServeHTTP(rec, req)
+	require.Equal(t, http.StatusOK, rec.Code)
+
+	var resp proxyDataResponse
+	require.NoError(t, json.Unmarshal(rec.Body.Bytes(), &resp))
+	require.Equal(t, 0, resp.Code)
+	require.Len(t, resp.Data.Proxies, 1)
+	require.Equal(t, "https", resp.Data.Proxies[0].Protocol)
+	require.Equal(t, "10.0.0.2", resp.Data.Proxies[0].Host)
+}
+
 func TestProxyImportDataReusesAndTriggersLatencyProbe(t *testing.T) {
 	router, adminSvc := setupProxyDataRouter()