fix(provider): 延长媒体超时并终止超时轮转

将图像和视频的默认 HTTP/轮询超时分别提高到 20 分钟和 30 分钟。媒体任务超时后直接失败，不再重试、切换客户端或标记为 upstream_submission_unknown。OpenAI 图像端点遇到上游明确拒绝 response_format 时自动移除并缓存兼容结论。

验证：go test ./... -count=1；go vet ./...；gofmt；相关 Shell bash -n、ShellCheck 与发布脚本回归测试。

apps/api/internal/clients/gemini.go

@@ -61,7 +61,7 @@ func (c GeminiClient) Run(ctx context.Context, request Request) (Response, error
 	}
 	resp, err := httpClient(request.HTTPClient, c.HTTPClient).Do(req)
 	if err != nil {
-		return Response{}, &ClientError{Code: "network", Message: err.Error(), Retryable: true}
+		return Response{}, transportClientError(err)
 	}
 	if err := notifyResponseReceived(request); err != nil {
 		return Response{}, err
@@ -294,7 +294,7 @@ func uploadOfficialGeminiImageFile(ctx context.Context, client *http.Client, can
 	startRequest.Header.Set("Content-Type", "application/json")
 	startResponse, err := client.Do(startRequest)
 	if err != nil {
-		return nil, &ClientError{Code: "network", Message: err.Error(), Retryable: true}
+		return nil, transportClientError(err)
 	}
 	if startResponse.StatusCode < http.StatusOK || startResponse.StatusCode >= http.StatusMultipleChoices {
 		_, responseErr := decodeHTTPResponse(startResponse)
@@ -314,7 +314,7 @@ func uploadOfficialGeminiImageFile(ctx context.Context, client *http.Client, can
 	uploadRequest.Header.Set("Content-Type", mimeType)
 	uploadResponse, err := client.Do(uploadRequest)
 	if err != nil {
-		return nil, &ClientError{Code: "network", Message: err.Error(), Retryable: true}
+		return nil, transportClientError(err)
 	}
 	result, err := decodeHTTPResponse(uploadResponse)
 	if err != nil {
@@ -392,7 +392,9 @@ func decodeGeminiStreamResponse(resp *http.Response, onDelta StreamDelta, wire *
 		}
 	}
 	if err := scanner.Err(); err != nil {
-		return nil, &ClientError{Code: "network", Message: err.Error(), Retryable: true, Wire: wire}
+		clientErr := transportClientError(err)
+		clientErr.Wire = wire
+		return nil, clientErr
 	}
 	if len(result) == 0 {
 		return nil, &ClientError{Code: "invalid_response", Message: "gemini stream returned no events", StatusCode: resp.StatusCode, Retryable: false, Wire: wire}