feat: 公共平台最小化打扰(design/12 §6)——5条策略: 分级+轻思考+限流+审查剔噪

降噪A(策略一/二/五):
- channelbridge/light.go: 非owner分级门——小事件当系统消息登记(不进loop)、非owner轻响应(她判断回/不回,规则优先mention/关键词+轻LLM兜底fail-closed静默)
- backthink 触发降噪: SubjectSystemEvent 低价值不唤醒thinking(仅高价值/owner才think), iot/reminder不受影响
- quiet hours: 安静时段非owner无信号静默,被@才回(非硬性静默); config QUIET_START/END_HOUR 单源共用

限流B(策略三/四):
- adapter/flowgate.go: per-adapter 滑窗限流器+总上限+审查剔噪闸门(Admit两连:速率+上限/审查), owner私聊绕过
- channelbridge/flowgate.go: onMessage入站最前挂闸, 超限/被剔不占worker槽; 审查模型NewLLMReviewer复用model.Adapter(仅>80%阈值触发+跨分钟节流,失败回退FIFO,绝不判身份)
- config: ChannelAccount 加 GroupMsgPerMin(默认6)/MsgPerMin/MaxMessages(默认50), CHANNELS_JSON每账号, 向后兼容
- 被剔消息走OnRejected审计不静默丢

main wire接线: 加modelAdapter字段+Review注入(reviewFor nil-safe,无LLM回退FIFO)
全仓 go build/vet/test 绿(53包)+交叉编译, 零新依赖, 前端无涉

internal/services/channelbridge/channelbridge_test.go

@@ -84,12 +84,17 @@ func (s *stubSessions) GetOrCreate(_ context.Context, msg adapter.UnifiedMessage
 	return s.sess, nil
 }
 
+// directMessage is an owner-private direct message: the sender is tagged as the
+// owner (structural, not from text), so it exercises the owner-private path. The
+// single-account stub session in newTestBridge reports Owner=true to match, since
+// the production SessionManager derives Owner from the resolved actor.
 func directMessage() adapter.UnifiedMessage {
 	return adapter.UnifiedMessage{
 		Platform:    "telegram",
 		ChannelID:   "100",
 		ChannelType: adapter.ChannelDirect,
 		SenderID:    "100",
+		Sender:      adapter.Actor{Role: adapter.RoleOwner},
 		Content:     "hello",
 		ContentType: adapter.ContentText,
 	}
@@ -180,6 +185,8 @@ func TestProcessGroupMessageKeepsGroupTarget(t *testing.T) {
 	t.Parallel()
 
 	b, chat, _, ad := newTestBridge(t)
+	// A non-owner group message that is addressed (mentioned) gets a response under
+	// design/12 §6 策略二, so it still exercises group reply targeting.
 	msg := adapter.UnifiedMessage{
 		Platform:    "telegram",
 		ChannelID:   "-20",
@@ -187,6 +194,8 @@ func TestProcessGroupMessageKeepsGroupTarget(t *testing.T) {
 		GroupID:     "-20",
 		GroupName:   "Gang",
 		SenderID:    "9",
+		Sender:      adapter.Actor{Role: adapter.RoleMember},
+		Mentions:    []adapter.Mention{{UserID: "9"}},
 		Content:     "hello all",
 		ContentType: adapter.ContentText,
 	}
@@ -351,10 +360,13 @@ func TestGroupMessageNotPersistedToMainSession(t *testing.T) {
 		t.Fatalf("New: %v", err)
 	}
 
+	// Addressed (mentioned) group message → responds (design/12 §6 策略二), still
+	// isolated to the group session.
 	msg := adapter.UnifiedMessage{
 		Platform: "telegram", ChannelID: "-20", ChannelType: adapter.ChannelGroup,
-		GroupID: "-20", GroupName: "Gang", SenderID: "9", Content: "hello all",
-		ContentType: adapter.ContentText,
+		GroupID: "-20", GroupName: "Gang", SenderID: "9",
+		Sender: adapter.Actor{Role: adapter.RoleMember}, Mentions: []adapter.Mention{{UserID: "9"}},
+		Content: "hello all", ContentType: adapter.ContentText,
 	}
 	b.process(context.Background(), msg)
 
@@ -463,11 +475,13 @@ func TestGroupMessageThirdPartySenderNameAndBoundary(t *testing.T) {
 		t.Fatalf("New: %v", err)
 	}
 
+	// Addressed (mentioned) group message → responds (design/12 §6 策略二), so the
+	// third-party boundary and the [第三方 · 张三] prefix are injected.
 	msg := adapter.UnifiedMessage{
 		Platform: "telegram", ChannelID: "-20", ChannelType: adapter.ChannelGroup,
 		GroupID: "-20", GroupName: "Gang", SenderID: "9", SenderName: "张三",
-		Sender: adapter.Actor{Role: adapter.RoleMember}, Content: "hello all",
-		ContentType: adapter.ContentText,
+		Sender: adapter.Actor{Role: adapter.RoleMember}, Mentions: []adapter.Mention{{UserID: "9"}},
+		Content: "hello all", ContentType: adapter.ContentText,
 	}
 	b.process(context.Background(), msg)