Documentation now describes the .NET Framework 4.8 stack (was .NET 8):
- README build prerequisites + framework-dependent/no-runtime-install note,
test count 136 -> 241.
- PLAN.md architecture diagram, stack decision (with PolySharp/shims note),
suite total 136 -> 241.
- deploy/README-DEPLOY.txt: app is net48 framework-dependent (4.8 is in-box on
Win10/11), and build prerequisites.
Also migrate the three tools (RioJoySmokeTest, RioSerialMonitor, XcfRegionExtract)
to net48 so they keep building against the now-net48 RioJoy.Core (a net8 project
cannot reference a net48 one). Added PolySharp + System.Memory/System.Text.Json
shims and replaced net-core-only APIs (string.Contains/IndexOf with comparison,
Array.Fill, generic Enum.IsDefined, int.TryParse(span)). All three build clean.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>