fix(acceptance): 阻断本地控制面漂移污染验收

本地 K3s 节点此前在 Kubelet 中登记为宿主机资源，负载可挤压 etcd 并在 server 重启后继续污染同一 Run。现在为三节点设置真实可调度预算、独立 etcd/数据卷和锁定依赖镜像，并持续核对 server 与 API/etcd 健康。\n\n每次验收生成独立 Run ID，报告使用独占或原子写入，负载错误记录具体阶段；数据库鉴权不可用返回带 Retry-After 的 503，避免基础设施故障被误报为 401。\n\n验证：Go 全量测试、go vet、gofmt、OpenAPI、bash -n、ShellCheck、报告测试和 k3d 配置解析均通过。

apps/api/internal/httpapi/volces_compat_handlers.go

@@ -28,6 +28,7 @@ const volcesContentsCompatibilityMarker = "volces_contents_generations_v3"
 // @Failure 401 {object} VolcesErrorEnvelope
 // @Failure 429 {object} VolcesErrorEnvelope
 // @Failure 502 {object} VolcesErrorEnvelope
+// @Failure 503 {object} VolcesErrorEnvelope
 // @Router /api/v1/contents/generations/tasks [post]
 func (s *Server) createVolcesContentsGenerationTask(w http.ResponseWriter, r *http.Request) {
 	user, ok := auth.UserFromContext(r.Context())
@@ -186,6 +187,7 @@ func (s *Server) createLegacyVolcesVideoGeneration(w http.ResponseWriter, r *htt
 // @Success 200 {object} EasyAIGeneratedResponse
 // @Failure 404 {object} EasyAIGeneratedResponse
 // @Failure 410 {object} EasyAIGeneratedResponse
+// @Failure 503 {object} ErrorEnvelope
 // @Router /api/v1/ai/result/{taskID} [get]
 func (s *Server) getEasyAITaskResult(w http.ResponseWriter, r *http.Request) {
 	user, ok := auth.UserFromContext(r.Context())