Read terminal size without invoking stty

[MikeMcQuaid]

• Query stdin with IO#winsize so uutils stty cannot stop in a background process group and hang Homebrew commands.
• Preserve cached results and fallbacks for redirected stdin or failed terminal queries, with regression coverage.

Fixes #23951

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Codex with GPT 6 Astra at Extra High effort, with local review and testing.

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[Copilot]

🟡 Changes recommended

Closed stdin raises an unhandled IOError, preventing existing size fallbacks.

Get a fresh assessment by requesting another Copilot review.

Pull request overview

Replaces stty size subprocess calls with Ruby’s direct terminal-size API.

Changes:

• Reads and caches stdin terminal dimensions via IO#winsize.
• Adds regression coverage for redirection, failures, memoisation and concurrency.

File summaries

File	Description
Library/Homebrew/utils/tty.rb	Queries terminal size without spawning stty.
Library/Homebrew/test/utils/tty_spec.rb	Tests the new terminal-size behaviour.

Review details

• Files reviewed: 2/2 changed files
• Comments generated: 1
• Review effort level: Balanced

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