fix(messaging): synchronize StreamingMessageHandler NetMQ socket sends

[Tyagiquamar]

Description

Synchronize NetMQ PushSocket sends and disposal in StreamingMessageHandler using a dedicated lock object (_socketLock).

Related Issue

Fixes #9790

Motivation and Context

StreamingMessageHandler.Transmit(Packet packet) sends packets over ZeroMQ via _server.SendMultipartMessage(message) on a NetMQ PushSocket. NetMQ sockets are not thread-safe. When multiple threads (such as algorithm execution and worker/result streaming threads) invoke Transmit or Send concurrently, concurrent NetMQ operations corrupt internal message buffers, crashing the process with NetMQException: Cannot close an uninitialised Msg.

Adding _socketLock synchronizes calls to _server?.SendMultipartMessage(message) and synchronizes resource clean-up during Dispose().

Requires Documentation Change

No

How Has This Been Tested?

• Verified compilation and static analysis in Docker matching .NET 10.0 runtime (dotnet build Messaging/QuantConnect.Messaging.csproj -c Release) exiting cleanly with 0 errors.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• Refactor (non-breaking change which improves implementation)
• Performance (non-breaking change which improves performance. Please add associated performance test and results)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Non-functional change (xml comments/documentation/etc)

Checklist:

• My code follows the code style of this project.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.
• My branch follows the naming convention bug-<issue#>- or feature-<issue#>-