Keep download progress within terminal width

[MikeMcQuaid]

Fixes #23370

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[Copilot]

Pull request overview

This PR fixes a TTY rendering edge case where download progress output can reach the final terminal column and trigger autowrap/erase behavior, causing the last character (e.g. the “B” in “MB”) to disappear.

Changes:

• Reduce the progress-message renderable width by one column to avoid writing into the terminal’s final column.
• Add a regression spec asserting the rendered progress line stays within Tty.width - 1 visible columns.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
Library/Homebrew/download_queue.rb	Adjusts progress rendering width to keep output within terminal bounds.
Library/Homebrew/test/download_queue_spec.rb	Adds a regression test for the “final column” progress rendering behavior.

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