fix(notify): 根治低带宽控制面阻塞与传输写入卡死

- 为控制消息增加优先级、公平调度、队列字节预算和自适应批处理
- 支持可取消的写门等待，收紧 shared/dedicated bulk、stream 和 Reply 写入边界
- 修复 bulk reset/close、连接 handoff 和安全 profile 切换时序
- 保留旧取消与超时错误契约，新增阶段化 TransportSendError
- 增加 ReplyCtx、ReplyObjCtx、写超时配置及黑洞连接和竞态回归测试

server.go

@@ -22,6 +22,7 @@ type ServerCommon struct {
 	stopCtx                        context.Context
 	maxReadTimeout                 time.Duration
 	maxWriteTimeout                time.Duration
+	replyWriteTimeout              atomic.Int64
 	parallelNum                    int
 	wg                             stario.WaitGroup
 	peerRegistry                   *serverPeerRegistry
@@ -47,6 +48,7 @@ type ServerCommon struct {
 	peerAttachAuthRejectCount      atomic.Int64
 	peerAttachDowngradeRejectCount atomic.Int64
 	peerAttachBindingRejectCount   atomic.Int64
+	linkMu                         sync.RWMutex
 	linkFns                        map[string]func(message *Message)
 	defaultFns                     func(message *Message)
 	noFinSyncMsgMaxKeepSeconds     int64
@@ -62,6 +64,8 @@ type ServerCommon struct {
 	recordRuntime                  *recordRuntime
 	bulkRuntime                    *bulkRuntime
 	bulkOpenTuning                 BulkOpenTuning
+	udpWriteGateOnce               sync.Once
+	udpWriteGate                   chan struct{}
 	bulkDedicatedSidecarMu         sync.Mutex
 	bulkDedicatedSidecars          map[*LogicalConn]map[uint32]*bulkDedicatedSidecar
 	connectionRetryState           *connectionRetryState
@@ -78,6 +82,7 @@ func NewServer() Server {
 	server.parallelNum = 0
 	server.noFinSyncMsgMaxKeepSeconds = 0
 	server.maxHeartbeatLostSeconds = 300
+	server.replyWriteTimeout.Store(int64(defaultMessageReplyWriteTimeout))
 	server.stopCtx, server.stopFn = context.WithCancel(context.Background())
 	server.SecretKey = nil
 	server.handshakeRsaKey = defaultRsaKey