Add list versions JSON

[MikeMcQuaid]

• Avoid Ruby startup for inventory-only JSON output.
• Emit formulae and casks from fast filesystem state via jq.
• Include nullable linked, opt-linked and pinned versions.
• Source list.sh in tests to avoid checkout Cellar state.
• Document --json for manpages while Ruby fails if reached.
• Cover combined, filtered, empty and missing-jq cases.

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[Copilot]

Pull request overview

This PR adds a new fast-path JSON output mode for brew list --versions --json, aiming to avoid Ruby startup by emitting installed formula/cask inventory directly from filesystem state and formatting via jq.

Changes:

• Implement brew list --versions --json in Library/Homebrew/list.sh, producing JSON for formulae/casks including linked/opt-linked/pinned versions.
• Add --json flag plumbing/documentation across Ruby CLI help, manpages, docs, and shell completions.
• Add integration tests covering combined output, filtering, empty output, missing jq, and Ruby fallback failure.

Reviewed changes

Copilot reviewed 8 out of 9 changed files in this pull request and generated 7 comments.

Show a summary per file

File	Description
manpages/brew.1	Documents brew list --json in the manpage.
docs/Manpage.md	Documents brew list --json in the docs manpage.
Library/Homebrew/list.sh	Implements the fast Bash JSON inventory output using jq.
Library/Homebrew/cmd/list.rb	Adds --json switch and blocks Ruby execution if reached.
Library/Homebrew/test/cmd/list_spec.rb	Adds test coverage for the new JSON output behavior and error cases.
Library/Homebrew/sorbet/rbi/dsl/homebrew/cmd/list.rbi	Adds Sorbet RBI for json? args helper.
completions/zsh/_brew	Adds --json completion for brew list.
completions/fish/brew.fish	Adds --json completion for brew list.
completions/bash/brew	Adds --json completion for brew list.

Files not reviewed (1)

• Library/Homebrew/sorbet/rbi/dsl/homebrew/cmd/list.rbi: Language not supported

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