fix(doubao-video): parse camelCase fields from Volcengine task responses

The taskdoubao adaptor expected snake_case JSON keys (video_url,
completion_tokens, total_tokens, framespersecond, service_tier,
created_at, updated_at) but Volcengine returns camelCase (videoUrl,
completionTokens, totalTokens, framesPerSecond, serviceTier,
createdAt, updatedAt). As a result the video URL was never parsed:
successful tasks fell back to the platform proxy URL
(BuildProxyURL) as result_url, which broke the video proxy in
containerized deployments (localhost:port not reachable inside the
container) and zeroed the usage tokens used for billing.

Align the responseTask JSON tags with the real Volcengine response
shape and add a regression test with the exact production payload.

Co-Authored-By: ZCode <noreply@anthropic.com>

relay/channel/task/doubao/adaptor.go

@@ -71,24 +71,24 @@ type responseTask struct {
 	Model   string `json:"model"`
 	Status  string `json:"status"`
 	Content struct {
-		VideoURL string `json:"video_url"`
+		VideoURL string `json:"videoUrl"`
 	} `json:"content"`
 	Seed            int    `json:"seed"`
 	Resolution      string `json:"resolution"`
 	Duration        int    `json:"duration"`
 	Ratio           string `json:"ratio"`
-	FramesPerSecond int    `json:"framespersecond"`
-	ServiceTier     string `json:"service_tier"`
+	FramesPerSecond int    `json:"framesPerSecond"`
+	ServiceTier     string `json:"serviceTier"`
 	Usage           struct {
-		CompletionTokens int `json:"completion_tokens"`
-		TotalTokens      int `json:"total_tokens"`
+		CompletionTokens int `json:"completionTokens"`
+		TotalTokens      int `json:"totalTokens"`
 	} `json:"usage"`
 	Error struct {
 		Code    string `json:"code"`
 		Message string `json:"message"`
 	} `json:"error"`
-	CreatedAt int64 `json:"created_at"`
-	UpdatedAt int64 `json:"updated_at"`
+	CreatedAt int64 `json:"createdAt"`
+	UpdatedAt int64 `json:"updatedAt"`
 }
 
 // ============================

relay/channel/task/doubao/adaptor_test.go

@@ -13,8 +13,8 @@ func TestParseTaskResult_SuccessWithUsage(t *testing.T) {
 	adaptor := &TaskAdaptor{}
 	taskInfo, err := adaptor.ParseTaskResult([]byte(`{
 		"status":"succeeded",
-		"content":{"video_url":"https://example.test/video.mp4"},
-		"usage":{"completion_tokens":12,"total_tokens":3456}
+		"content":{"videoUrl":"https://example.test/video.mp4"},
+		"usage":{"completionTokens":12,"totalTokens":3456}
 	}`))
 
 	require.NoError(t, err)
@@ -28,7 +28,7 @@ func TestParseTaskResult_SuccessWithoutUsage(t *testing.T) {
 	adaptor := &TaskAdaptor{}
 	taskInfo, err := adaptor.ParseTaskResult([]byte(`{
 		"status":"succeeded",
-		"content":{"video_url":"https://example.test/video.mp4"}
+		"content":{"videoUrl":"https://example.test/video.mp4"}
 	}`))
 
 	require.NoError(t, err)
@@ -241,6 +241,38 @@ func TestConvertToOpenAIVideo_FailedUsesUpstreamError(t *testing.T) {
 	require.Contains(t, string(data), `"code":"InvalidParameter"`)
 }
 
+// Parses the exact Volcengine response shape observed in production:
+// camelCase videoUrl / usage tokens, not snake_case.
+func TestParseTaskResult_RealVolcengineResponse(t *testing.T) {
+	adaptor := &TaskAdaptor{}
+	taskInfo, err := adaptor.ParseTaskResult([]byte(`{
+		"id":"cgt-20260819170015-glgnd",
+		"seed":46303,
+		"draft":false,
+		"model":"doubao-seedance-2-0-260128",
+		"ratio":"16:9",
+		"usage":{"totalTokens":216900,"completionTokens":216900},
+		"status":"succeeded",
+		"content":{"videoUrl":"https://ark-acg-cn-beijing.tos-cn-beijing.volces.com/output.mp4"},
+		"duration":10,
+		"priority":0,
+		"createdAt":1787130015,
+		"updatedAt":1787130344,
+		"resolution":"720p",
+		"serviceTier":"default",
+		"outputFormat":"mp4",
+		"generateAudio":false,
+		"framesPerSecond":24,
+		"executionExpiresAfter":172800
+	}`))
+
+	require.NoError(t, err)
+	require.Equal(t, string(model.TaskStatusSuccess), taskInfo.Status)
+	require.Equal(t, "https://ark-acg-cn-beijing.tos-cn-beijing.volces.com/output.mp4", taskInfo.Url)
+	require.Equal(t, 216900, taskInfo.CompletionTokens)
+	require.Equal(t, 216900, taskInfo.TotalTokens)
+}
+
 func TestGetModelList_IncludesSeedance20Models(t *testing.T) {
 	adaptor := &TaskAdaptor{}
 	models := adaptor.GetModelList()