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

bulk_fastpath.go

@@ -370,7 +370,7 @@ func (s *ServerCommon) sendFastBulkDataTransport(ctx context.Context, logical *L
 	if err != nil {
 		return err
 	}
-	return s.writeEnvelopePayload(logical, transport, nil, payload)
+	return s.writeEnvelopePayloadContext(ctx, logical, transport, nil, payload)
 }
 
 func (s *ServerCommon) sendFastBulkWriteTransport(ctx context.Context, logical *LogicalConn, transport *TransportConn, dataID uint64, startSeq uint64, chunkSize int, fastPathVersion uint8, payload []byte, payloadOwned bool) (int, error) {
@@ -439,7 +439,7 @@ func (s *ServerCommon) sendFastBulkControlTransport(ctx context.Context, logical
 	if err != nil {
 		return err
 	}
-	return s.writeEnvelopePayload(logical, transport, nil, encoded)
+	return s.writeEnvelopePayloadContext(ctx, logical, transport, nil, encoded)
 }
 
 func (s *ServerCommon) encodeBulkFastControlPayloadLogical(logical *LogicalConn, frameType uint8, flags uint8, dataID uint64, seq uint64, payload []byte) ([]byte, error) {
@@ -474,6 +474,9 @@ func transportFastPayloadMagic(payload []byte) string {
 
 func (c *ClientCommon) decryptTransportPayloadPooled(payload []byte, release func()) ([]byte, func(), error) {
 	profile := c.clientTransportProtectionSnapshot()
+	if fallback := c.inboundTransitionProfile.Load(); fallback != nil {
+		return decryptTransportPayloadWithFallbackPooled(profile, *fallback, payload, release)
+	}
 	return decryptTransportPayloadCodecPooled(profile.mode, profile.runtime, profile.msgDe, profile.secretKey, payload, release)
 }
 
@@ -484,9 +487,35 @@ func (s *ServerCommon) decryptTransportPayloadLogicalPooled(logical *LogicalConn
 		}
 		return nil, nil, errTransportDetached
 	}
+	if fallback := logical.inboundTransitionProfile.Load(); fallback != nil {
+		profile := logical.transportProtectionProfileSnapshot()
+		return decryptTransportPayloadWithFallbackPooled(profile, *fallback, payload, release)
+	}
 	return decryptTransportPayloadCodecPooled(logical.protectionModeSnapshot(), logical.modernPSKRuntimeSnapshot(), logical.msgDeSnapshot(), logical.secretKeySnapshot(), payload, release)
 }
 
+func decryptTransportPayloadWithFallbackPooled(primary transportProtectionProfile, fallback transportProtectionProfile, payload []byte, release func()) ([]byte, func(), error) {
+	profiles := [...]transportProtectionProfile{primary, fallback}
+	for _, profile := range profiles {
+		plain, plainRelease, err := decryptTransportPayloadCodecOwnedPooled(profile.mode, profile.runtime, profile.msgDe, profile.secretKey, payload)
+		if err != nil {
+			continue
+		}
+		if profile.mode == ProtectionExternal {
+			plain = append([]byte(nil), plain...)
+			plainRelease = nil
+		}
+		if release != nil {
+			release()
+		}
+		return plain, plainRelease, nil
+	}
+	if release != nil {
+		release()
+	}
+	return nil, nil, errTransportPayloadDecryptFailed
+}
+
 func (c *ClientCommon) tryDispatchBorrowedTransportPlain(plain []byte, release func()) bool {
 	switch transportFastPayloadMagic(plain) {
 	case bulkFastPayloadMagic, bulkFastBatchMagic: