production runtime and mock removal

lib/seedance/client.ts

@@ -46,13 +46,6 @@ export function getSeedanceConfig() {
   };
 }
 
-export function shouldMockSeedance() {
-  const flag = process.env.SEEDANCE_MOCK || "auto";
-  if (flag === "1" || flag === "true") return true;
-  if (flag === "0" || flag === "false") return false;
-  return !getSeedanceConfig().apiKey;
-}
-
 export async function createSeedanceTask(input: SeedanceCreateInput) {
   const config = getSeedanceConfig();
   if (!config.apiKey) throw new Error("缺少 SEEDANCE_API_KEY。请在 .env.local 配置火山方舟 API Key。");