Update DB config, docs, and SignalR binary protocol setup
- Switched appsettings.json connection string to production DB.
- Added "Shared Agent Skills" section to copilot-instructions.md in both main and Mango.Nop Libraries repos.
- Refactored PluginNopStartup.cs: improved using statements, updated SignalR to use AddAcBinaryProtocol with explicit options, removed manual IHubProtocol registration, and added protocol diagnostics.
- No business logic changes; focused on configuration, documentation, and infrastructure.
Loretta
8d3c2a8462