Show a numbered menu off Windows instead of crashing [patch]

[matt-edmondson]

Fixes #165

What changed

Menu is the default verb. It displays a DustInTheWind ScrollMenu, which reads Console.CursorVisible, and .NET only supports that on Windows. So ImageDescriber with no arguments, or with an unknown verb, died with PlatformNotSupportedException (exit 134) on Linux and macOS.

• Windows: unchanged. It still uses the ScrollMenu.
• Other platforms: a numbered prompt menu (Menu.RunPromptMenu) lists the other verbs plus Exit and reads the choice from standard input:
  • it runs the chosen verb, then shows the menu again;
  • it rejects anything that isn't a number in range;
  • it stops at end of input, so piped or closed stdin can't loop forever.
• Building the item text and the verb instance is split out of CreateMenuItem, so both menus share it.

On Linux, the built binary with no arguments now shows:

1. Configure - Configure the Ollama endpoint and model settings.
...
6. Stats - Show database statistics.
7. Exit
Choose an option:

Tests

New MenuTests.cs:

• RunWithoutArgumentsOffersMenuOffWindows runs the real Menu verb with stdin and stdout redirected. With Menu.cs reverted, it fails with System.PlatformNotSupportedException: Operation is not supported on this platform. With the fix, it passes. It is Inconclusive on Windows, where the ScrollMenu needs a real console.
• PromptMenuRunsTheChosenItemUntilExit, PromptMenuRejectsInvalidChoices and PromptMenuStopsAtEndOfInput cover the prompt loop.

Full suite: 50 passed.

The triage note links this to #167 (non-zero exit codes). This PR doesn't touch exit codes; the menu path has no error exit of its own.

🤖 Generated with Claude Code

https://claude.ai/code/session_01QtRTdtw1SbV7ugjz5wPFgc

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Generated by Claude Code

[sonarqubecloud]

Quality Gate passed

Issues
8 New issues
0 Accepted issues

Measures
0 Security Hotspots
84.6% Coverage on New Code
0.0% Duplication on New Code

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