fix(TextPrompt): prevent ArgumentOutOfRangeException for non-ASCII default values

[Moha-sami]

Fixes #2152

• I have read the Contribution Guidelines
• I have checked that there isn't already another pull request that solves the above issue
• All newly added code is adequately covered by tests
• All existing tests are still running without errors

Changes

Problem

When using TextPrompt with EditableDefaultValue(true) containing non-ASCII or Unicode characters (e.g. "日本語" or "ä"), AnsiConsoleExtensions.Input.cs passed (ConsoleKey)ch to ConsoleKeyInfo, which throws ArgumentOutOfRangeException in .NET when ConsoleKey > 255.

Solution

1. Updated AnsiConsoleExtensions.Input.cs to check (int)ch <= 255 ? (ConsoleKey)ch : (ConsoleKey)0, preventing out-of-range exceptions while maintaining full Unicode string processing.
2. Added unit test Should_Not_Throw_When_Editable_Default_Value_Contains_Non_Ascii_Characters in TextPromptTests.cs.

[Moha-sami]

@microsoft-github-policy-service agree

[patriksvensson]

Thanks for opening this pull request. Before I can review it, the pull request template needs to be fully filled out so I have all the necessary context.

I’m going to close this for now, but feel free to update the template and reopen the PR once everything is completed as expected. Thanks!