Accept one-key ask confirmations

[MikeMcQuaid]

• Allow brew --ask prompts to proceed from y or Y.
• Abort from n or N without waiting for a newline.
• Treat Escape, Ctrl-D and Ctrl-C as quiet cancellation.
• Reprompt after other keys so users choose explicitly.

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[Copilot]

Pull request overview

Switches the brew --ask confirmation prompt from line-buffered gets (requires Enter) to single-keypress getch, so a lone y/Y proceeds and n/N/Enter aborts without needing Return.

Changes:

• Replace $stdin.gets with $stdin.getch in ask_input, drop the yes/no word forms, and update the invalid-input hint accordingly.
• require "io/console" in install.rb to enable IO#getch.
• Update existing ask specs to stub getch and add new specs covering y/Y accept and n/N decline single-key paths.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
Library/Homebrew/install.rb	Adds io/console require and rewrites the ask prompt loop to read a single character, accepting only y and treating blank/n as abort.
Library/Homebrew/test/cmd/install_spec.rb	Updates the default-no test to stub getch, adds accept/decline single-char tests, and updates the no-TTY test to assert getch is not called.

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