fix(runner): 修复图像结果转存与任务租约失效

修正非语义字段长 Base64 元数据被误判为媒体的问题，并允许按文件签名识别真实媒体后转存 OSS；同时将网关本地存储失败与上游失败分离，避免重复调用和错误降权。

异步任务复用已分配并发名额前立即刷新租约，租约已丢失时重新排队获取，避免排队耗时侵蚀租约后错误调用上游。生产环境关闭 server-main 尚未实现的进度回调，保留 Gateway 任务详情与事件查询。

验证：API 全量 go test、go vet、gofmt、Kubernetes 渲染、迁移安全检查及真实阿里云 OSS 读写/生命周期验收通过。

apps/api/internal/runner/retry_decision.go

@@ -303,16 +303,16 @@ func priorityDemoteDecisionForCandidate(runnerPolicy store.RunnerPolicy, err err
 }
 
 func isResultPersistenceFailure(err error) bool {
-	switch strings.ToLower(strings.TrimSpace(clients.ErrorCode(err))) {
-	case "local_result_storage_unavailable",
-		"binary_result_too_large",
-		"binary_result_corrupted",
-		"binary_result_expired",
-		"result_binary_not_materialized":
-		return true
-	default:
-		return false
-	}
+	return isGatewayResultPersistenceCode(clients.ErrorCode(err))
+}
+
+func isGatewayResultPersistenceCode(code string) bool {
+	code = strings.ToLower(strings.TrimSpace(code))
+	return strings.HasPrefix(code, "storage_") ||
+		strings.HasPrefix(code, "upload_") ||
+		strings.HasPrefix(code, "binary_result_") ||
+		strings.HasPrefix(code, "local_result_") ||
+		strings.HasPrefix(code, "result_binary_")
 }
 
 func effectiveFailoverPolicy(base map[string]any, override map[string]any) map[string]any {
@@ -353,6 +353,8 @@ func failureCategory(code string, status int, message string) string {
 	switch {
 	case code == "insufficient_balance":
 		return "insufficient_balance"
+	case isGatewayResultPersistenceCode(code):
+		return "gateway_storage"
 	case code == "rate_limit" || status == 429:
 		return "rate_limit"
 	case code == "network":