[jmaeagle99]

What was changed

Samples and the standalone test runner now parse their arguments with System.CommandLine instead of hand-rolled args switches. Command names are unchanged, so the README instructions still work.

Behavior differences:

• --help works everywhere, and it, like argument errors, no longer needs a running server.
• Running with no command (or an unknown one) prints help and exits 1, instead of throwing.
• Ctrl+C is handled through System.CommandLine's cancellation token rather than each sample's own Console.CancelKeyPress handler.
• Patching now has the --workflow / --start-workflow / --query-workflow options its README already documented.
• ClientMtls gen-client-certs now accepts --file-prefix and the CA options, which were previously never registered.
• WorkerVersioning command names are now case-sensitive.

Why?

• Each sample had its own slightly different hand-written parser, with no --help and inconsistent errors. A mistyped command produced a stack trace, often after connecting to the server.
• That kind of parsing can't reject arguments it doesn't recognize, so code and READMEs drifted apart unnoticed. Patching documented --workflow / --start-workflow options that the code silently ignored.
• ClientMtls was already on System.CommandLine, but a 2022 beta whose API changed in the 2.0 release. This moves everything onto one consistent, current pattern.

Checklist

1. Closes Use System.CommandLine for arg parsing #239

2. Any docs updates needed? No