feat(runtime+admin): A2 LLM异步提取接线 + A4 Tracing接线 + A6通知后端聚合

A2 异步记忆提取:
- loop/memory.go: asyncExtractor接口(ExtractAsync)+extractMemoryAsync(60s超时,WithOutCancel,dispatch即返回,后台落库,失败仅Warn)+persistMemories共用
- run.go 三个回合落定点改异步提取; 删除run.go逐步提取(design/03'每轮后', 避免多轮工具N次LLM调用/重复写)
- cmd/cyrene/extractor.go buildMemoryExtractor: llmGroupUsable为真→LLMExtractor, 否则回落ManualExtractor(日志说明); keylessEndpoint放行loopback/私网

A4 可观测性 Tracing:
- cmd/cyrene/observability.go: newAppTraceWriter+traceFanout(多sink)+gatewaySpanSink(走gw.ObserveSpan,喂环形缓冲+LLM/subagent指标)
- wire.go 注入; 未改trace/gateway数据结构

A6 通知后端:
- internal/services/gateway/notifications.go(311行): GET /admin/notifications?type=&before=&limit= (adminAuth)
- 聚合已有源(obs.audit SQLite + s.backthink), createdAt倒序, id=source:id; 类型派生(channel/system/audit/backthink); 无新建表/无新Deps/wire零改动
- 诚实: backthink仅shouldPush计, 未注入源为空, 报错500, 未读游标后置
- 契约与前端Y一致: {id,type,title,body,source,createdAt}, before含游标(<=), type未知400
- Docs/api-client v0.33

全仓 build/vet/test绿(56包)+win/darwin/linux-arm64交叉编译绿; 新增测试(memory_async/extractor/observability/notifications)

internal/services/gateway/server.go

@@ -515,6 +515,10 @@ func (s *Server) Handler() http.Handler {
 	mux.Handle("GET /api/v1/admin/observability/metrics", adminAuth(http.HandlerFunc(s.adminObservabilityMetrics)))
 	mux.Handle("GET /api/v1/admin/observability/trace", adminAuth(http.HandlerFunc(s.adminObservabilityTrace)))
 	mux.Handle("GET /api/v1/admin/observability/audit", adminAuth(http.HandlerFunc(s.adminObservabilityAudit)))
+	// Unified notification feed (design/10 §3 #16): a read-only projection of the
+	// audit trail + backthink pushes, so the panel's notification page needs no
+	// new persisted model.
+	mux.Handle("GET /api/v1/admin/notifications", adminAuth(http.HandlerFunc(s.adminListNotifications)))
 	mux.Handle("POST /api/v1/admin/plugins/policy", s.auth.Authorize(auth.RoleOwner)(http.HandlerFunc(s.adminSetPolicy)))
 
 	// Admin writes: owner-only, audited. Reads above accept owner/admin; writes