feat(backthink): 主动推送 sink 打通——hub.SendProactive + bridge.SendProactive + wire 接线

backthink 决策+路由(P2)就绪但无投递 sink(ActiveClient/IMAdapter 无实现)。补齐:
- gateway/proactive.go: hub.SendProactive 向 owner/admin 连接广播 proactive_message WS事件,
  内容脱敏(去RawData/media/token),返回接收数,count=0→IM兜底;Server.SendProactive 委托
- channelbridge/proactive.go: Bridge.SendProactive 解析 owner 账户(msg.Platform→匹配白名单账号,
  否则首个已配置主人频道),ChannelType=Direct+ChannelID/SenderID=owner id,走 adapter.SendProactive
- backthink/sinks.go: SetActiveSink/SetIMSink 晚注入(New后重建pusher,currentPusher 并发安全)
- wire.go: 在 gw/bridge 建好后 bt.SetActiveSink(gw)/SetIMSink(bridge)
- 投递链: think→parseProactive→ShouldPush→currentPusher.Push→gate→active(active_client)/IM(im_bridge)
  →record(route+送达数)
- 测试: sinks/gateway proactive/channelbridge proactive; 后端 build/vet/test 全绿
- 注: -race 本机 TSan 不可用(环境); 多平台IM按msg.Platform匹配 owner 账号(单sink诚实);
  weixin 24h窗口按 ErrProactiveWindow 记录为 im_bridge 错误不静默

cmd/cyrene/wire.go

@@ -662,6 +662,18 @@ func (a *app) wireFrontend() error {
 	}
 	a.gw = gw
 	a.capacitySink = gw
+
+	// Wire the backthink proactive sinks now that the gateway hub (active-client
+	// route) and the channel bridge (IM fallback) both exist. They were absent when
+	// backthink.New ran (the hub needs the loop and the bridge needs the loop and the
+	// owner profile, all assembled later), so without this the pusher would resolve
+	// RouteNone. Each setter rebuilds the pusher under the service's lifecycle lock.
+	if a.backthink != nil {
+		a.backthink.SetActiveSink(gw)
+		if a.channelBridge != nil {
+			a.backthink.SetIMSink(a.channelBridge)
+		}
+	}
 	return nil
 }