Testing framework WIP and XeDSA signing infra

[thebentern]

No description provided.

[Copilot]

Pull Request Overview

This PR introduces a comprehensive testing framework and XEdDSA signing infrastructure for the Meshtastic C# library. The changes include device discovery capabilities, cryptographic signing features, and integration testing infrastructure to support real hardware testing scenarios.

• Device discovery system for Linux and macOS USB devices with Meshtastic vendor ID detection
• XEdDSA (Extended EdDSA) signing implementation for NodeInfo packet authentication
• Integration testing framework with hardware device support and automated discovery

Reviewed Changes

Copilot reviewed 19 out of 22 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
protobufs	Updated subproject commit reference
Meshtastic/Meshtastic.csproj	Added LibUsbDotNet package dependency
Meshtastic/Discovery/MeshtasticDevice.cs	Device model with hardware detection logic
Meshtastic/Discovery/DeviceDiscovery.cs	Cross-platform USB device discovery implementation
Meshtastic/Data/MessageFactories/NodeInfoMessageFactory.cs	Factory for creating signed NodeInfo messages
Meshtastic/Crypto/XEdDSASigning.cs	XEdDSA cryptographic signing implementation
Meshtastic.IntegrationTest/*	Complete integration testing framework
Directory.Packages.props	Added LibUsbDotNet package version

Comments suppressed due to low confidence (1)

Meshtastic/Crypto/XEdDSASigning.cs:55

• Missing using directive for System.Text. The code uses Encoding.ASCII.GetBytes() on line 55 but the using directive is not present at the top of the file.

        byte[] domain = Encoding.ASCII.GetBytes("XEdDSA");

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