Document Homebrew bottle release process

[codeforester]

Summary

• Update the release process so supported macOS releases publish Homebrew bottles before the tap PR is merged.
• Tighten the Homebrew upgrade rehearsal to require bottled upgrades on supported macOS hosts.
• Record the 2026-06-12 Intel Mac source-build sandbox failure and refresh release workflow AI context.

Issue

• Closes Publish Homebrew bottles for Base releases #608.
• Tap workflow implementation: Add Base Homebrew bottle workflow homebrew-base#11.
• Tap workflow fixes: Fix bottle workflow branch guard expression homebrew-base#12, Smoke test Base bottle workflow install homebrew-base#13, Fix bottle workflow artifact collection homebrew-base#14, Upload Homebrew bottle URL filenames homebrew-base#16.
• Base 0.4.4 bottle stanza: Add Base 0.4.4 Homebrew bottles homebrew-base#15.

Validation

• git diff --check
• env -u BASE_HOME ./bin/base-test
  • Python: 384 passed, 1 skipped
  • BATS/integration: 427 tests passed
• Build Base Bottles workflow passed: https://github.com/codeforester/homebrew-base/actions/runs/27430040271
• brew fetch --force-bottle codeforester/base/base

Demo Impact

• None. Release process and documentation only.

Notes

• .ai-context/ updated because this changes the durable release workflow.
• Local brew audit --new --formula Formula/base.rb for the tap PR was attempted but blocked on this Mac by Homebrew's Command Line Tools prerequisite gate, not by the workflow changes.