Reduce Intel macOS to Tier 3

[p-linnane]

Follow-up to #23677, which stopped routinely building Intel bottles in Homebrew/core. Tier 1 requires full CI coverage for testing and bottle builds, so Intel no longer qualifies.

brew doctor now reports Intel macOS as Tier 3, and we no longer point Intel users at the issue tracker. Outdated macOS still takes precedence over the new Intel finding, so those users keep the MacPorts remediation. The OpenCore Legacy Patcher check is removed: every Intel Mac is Tier 3 now, so it only duplicated the new finding without adding a classification.

fresh_install? is gated on Apple Silicon so Intel users fall back to source builds rather than hitting a hard "no bottle available!" error now that Intel bottles are gone. Portable Ruby still builds for Intel, so the docs say we have stopped routinely building Intel bottles rather than stopping outright.

The macOS .pkg now warns that Intel is a Tier 3 configuration instead of installing silently, and the stale "Intel keeps /usr/local bottling until EOL" note in the relocatable bottles plan is corrected. Companion pull requests will follow in Homebrew/install and Homebrew/brew.sh, which both still describe Intel as supported.

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• I did not use AI/LLM to create this PR, or I disclosed the tool/model below and reviewed its output; I did not attribute commits to AI and will answer maintainer questions and review comments myself without AI/LLM.

Claude Code (Opus 5) drafted the implementation and tests; I reviewed the diff, verified the new tests fail without the fix and pass with it, and ran brew lgtm plus targeted specs.

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[Copilot]

Pull request overview

Reclassifies Intel macOS as Tier 3 across Homebrew’s diagnostics, installation behavior, package installer, and documentation.

Changes:

• Reports Intel macOS as Tier 3 and suppresses issue-tracker guidance.
• Falls back to source builds when Intel bottles are unavailable.
• Updates installer warnings and support documentation.

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
package/Distribution.xml	Adds an Intel Tier 3 installer warning.
Library/Homebrew/test/os/mac/formula_installer_spec.rb	Tests Intel source-build fallback.
Library/Homebrew/test/os/mac/diagnostic_spec.rb	Tests Intel and outdated-macOS findings.
Library/Homebrew/plans/relocatable-bottles.md	Excludes routine Intel bottles from the plan.
Library/Homebrew/os.rb	Limits issue guidance to Tier 1 Apple Silicon.
Library/Homebrew/extend/os/mac/formula_installer.rb	Disables fresh-install bottle errors on Intel.
Library/Homebrew/extend/os/mac/diagnostic.rb	Adds Intel Tier 3 detection and removes OpenCore detection.
docs/Support-Tiers.md	Reclassifies Intel macOS and updates the timeline.
docs/Installation.md	Documents Intel installation as Tier 3.

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[MikeMcQuaid]

Looks good but let's land it in September, despite lack of bottling for now.

[MikeMcQuaid]

Looks good! Let's hold off merging until next release will be 6.1.0/7.0.0 (around 11th September).

[SMillerDev]

Maybe we should at least merge the docs change, as mentioned here: https://github.com/orgs/Homebrew/discussions/7044#discussioncomment-18217553 we do not currently communicate anywhere that Intel is Tier 3, except in the fact formulae are missing bottles.

[MikeMcQuaid]

@SMillerDev I want to wait until September. We can merge tomorrow.

[fxcoudert]

Can we introduce (here or as a follow-up) a specific warning with a link to explicit doc and guidance on the Intel EOL? Something like #23715

[MikeMcQuaid]

Can we introduce (here or as a follow-up) a specific warning with a link to explicit doc and guidance on the Intel EOL? Something like #23715

Yes 👍🏻

[fxcoudert]

Thanks @MikeMcQuaid for incorporating the improved, user-friendly explanation!

[MikeMcQuaid]

Looks good will merge tomorrow