Fix edgeHub MQTT connection timeouts caused by DotNetty downgrade

[Bilal Sellak (bilalsellak)]

Summary
Fixes an edgeHub MQTT/TLS failure where the client completes TLS and sends MQTT CONNECT, but edgeHub does not receive the decrypted MQTT packet and therefore never returns CONNACK.

Root cause
The .NET 10 and Device SDK update removed a transitive dependency that previously raised DotNetty to 0.7.6. Microsoft.Azure.Devices.ProtocolGateway.Core 2.0.1 still declares 0.6.0, causing NuGet to resolve the MQTT server stack back to DotNetty 0.6.0.

DotNetty 0.6.0 can lose application data received around TLS handshake completion, particularly when the final TLS flight and MQTT CONNECT arrive together with AutoRead=false.

Fix

• Add direct references to DotNetty.Codecs.Mqtt and DotNetty.Handlers 0.7.6.

Validation

• A controlled .NET 10 TLS reproduction produced:

• DotNetty 0.6.0, TLS + MQTT: 0/30 delivered

• DotNetty 0.7.6, same input: 30/30 delivered

Repository validation:

Release build succeeded.
All 192 MQTT unit tests passed.
Generated runtime manifest contains only DotNetty 0.7.6 packages.
No DotNetty 0.6.0 runtime assets remain.

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