Preserve cask choice zeroes

[MikeMcQuaid]

Fixes #22400

• Keep attributeSetting: 0 in internal API cask artifacts because installer choices need zero as a meaningful value.
• Allow Utils.deep_compact_blank callers to opt out of dropping zeroes while preserving existing default behaviour.

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[Copilot]

Pull request overview

This PR fixes internal API cask artifact serialization so that installer choice settings with attributeSetting: 0 are preserved (since 0 is a meaningful value for macOS installer choices), by making Utils.deep_compact_blank optionally retain numeric zeroes.

Changes:

• Add a compact_zero: keyword option to Utils.deep_compact_blank (defaulting to current behavior of compacting zeroes).
• Preserve zero values when compacting/serializing raw_artifacts in Homebrew::API::CaskStruct#serialize.
• Add a regression test ensuring attributeSetting: 0 survives serialization in cask artifacts.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
Library/Homebrew/utils.rb	Adds compact_zero: option to allow callers to preserve numeric zeroes while deep-compacting.
Library/Homebrew/api/cask_struct.rb	Ensures raw_artifacts serialization retains 0 values (notably attributeSetting: 0) while still compacting blanks elsewhere.
Library/Homebrew/test/api/cask_struct_spec.rb	Adds coverage to prevent regression for zero-valued installer choice settings in serialized artifacts.

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[Rylan12]

@MikeMcQuaid I wonder if not stripping out 0 values everywhere would be an okay choice. I know it's used for things like bottle rebuild and revision, but adding "revision": 0 to a whole bunch of formulae might not increase the compressed size very much... might be worth a try

[MikeMcQuaid]

@Rylan12 Yeh, if we encounter more bugs that's an option but would rather still omit for now.