fix(api): 视频生成 - 修正 Video Generations 时长字段类型

backend/internal/service/provider.go

@@ -1054,7 +1054,7 @@ func newAPIChannel2VideoBody(input canvasGenerationInput) (map[string]interface{
 	body := map[string]interface{}{
 		"model":          input.Config.Model,
 		"prompt":         strings.TrimSpace(input.Prompt),
-		"seconds":        seconds,
+		"seconds":        strconv.Itoa(seconds),
 		"aspect_ratio":   ratio,
 		"resolution":     resolution,
 		"generate_audio": parseBool(input.Config.VideoGenerateAudio, true),

backend/internal/service/provider_test.go

@@ -782,7 +782,7 @@ func TestRunNewAPIChannel2VideoTaskDownloadsTemporaryResult(t *testing.T) {
 			if err := json.NewDecoder(r.Body).Decode(&body); err != nil {
 				t.Fatalf("decode request: %v", err)
 			}
-			if body["model"] != "grok-image-video" || body["seconds"] != float64(10) || body["aspect_ratio"] != "9:16" || body["resolution"] != "720p" {
+			if body["model"] != "grok-image-video" || body["seconds"] != "10" || body["aspect_ratio"] != "9:16" || body["resolution"] != "720p" {
 				t.Errorf("body = %#v", body)
 			}
 			images, ok := body["image_urls"].([]interface{})