Reapply code cleanups on latest master

[EngstromJimmy]

Summary

• reapply the code-cleanup and API-signature work on top of current master across the core emulator and Meadow code
• keep the .NET 10 Blazor and MonoGame projects aligned, include the Currah ROM assets, and preserve the Currah opcode-fetch path after the rebase
• fix the Blazor Toolbelt Gamepad startup/runtime issues and preserve the GitHub Pages custom domain with a published CNAME file

Validation

• dotnet test ZXBox.Core.Tests\ZXBox.Core.Tests.csproj --filter "FullyQualifiedNameUnitTests|FullyQualifiedNameCoreTest" -v minimal -p:UseSharedCompilation=false
• dotnet build Platforms\ZXBox.Monogame\ZXBox.Monogame.csproj -v minimal -p:UseSharedCompilation=false
• dotnet publish Platforms\ZXBox.Blazor\ZXBox.Blazor.csproj -c Release -v minimal -p:UseSharedCompilation=false