Interactive prompts confirm a selection with ¬ (negation sign) #555

Problem

ConsoleUtility marks a confirmed prompt answer with the negation sign (src/Fallout.Build/Utilities/ConsoleUtility.cs:19):

private static string Confirmed => "¬";

It is printed in green after PromptForInput and PromptForChoice accept a value — so the glyph that means "not" is used to mean "accepted". Users hitting fallout :setup see it on every answer.

Outcome

A confirmed answer is marked with a glyph that reads as confirmation.

Acceptance criteria

• Confirmed prompt lines are prefixed with a check mark, not ¬
• The glyph is single-cell so the prompt lines stay aligned
• Specs cover the confirmation prefix for both PromptForInput and PromptForChoice

Notes

Keep it to a single-width glyph — the prompt writers pad to BufferWidth on raw character count, so a double-width glyph would shift the line. The broader kaomoji/icon vocabulary is separate (sub-issue of #391).