perf(storage): 极简化任务历史并增加保留治理

停止持久化 provider 原始响应、兼容响应快照、attempt/event/outbox 重复 JSON，并由标准任务结果动态生成 Kling/Keling/Volces 兼容响应。

增加事件去重与预算、极简 callback 投递、7/30 天分批清理、安全删除条件、并发迁移索引及可实际恢复的任务域排除备份。历史清理默认关闭，待兼容协议和异步恢复在线验证后单独启用。

验证：Go 全量测试与 go vet、PostgreSQL 18 集成与实际备份恢复、迁移安全测试、bash -n、ShellCheck、Compose 配置和人工发布脚本测试均通过。

apps/api/internal/securityevents/metrics_test.go

@@ -30,6 +30,8 @@ func TestMetricsExposeBoundedOutcomesAndState(t *testing.T) {
 	metrics.ObserveAsyncWorkerResize("success")
 	metrics.ObserveConcurrencyLeaseRenewal("success")
 	metrics.ObserveConcurrencyLeaseRenewal("lost")
+	metrics.ObserveTaskEventSkip("duplicate")
+	metrics.ObserveTaskEventSkip("budget_exceeded")
 
 	recorder := httptest.NewRecorder()
 	metrics.Handler(metricsSnapshot{mode: "push_healthy", last: time.Now().Add(-time.Minute)}, "issuer", "audience", true).
@@ -52,6 +54,8 @@ func TestMetricsExposeBoundedOutcomesAndState(t *testing.T) {
 		`easyai_gateway_async_worker_resizes_total{outcome="success"} 1`,
 		`easyai_gateway_concurrency_lease_renewals_total{outcome="success"} 1`,
 		`easyai_gateway_concurrency_lease_renewals_total{outcome="lost"} 1`,
+		`easyai_gateway_task_events_skipped_total{outcome="duplicate"} 1`,
+		`easyai_gateway_task_events_skipped_total{outcome="budget_exceeded"} 1`,
 	} {
 		if !strings.Contains(recorder.Body.String(), expected) {
 			t.Fatalf("missing metric %q in:\n%s", expected, recorder.Body.String())