ci: add homebrew install smoke lane (TIN-131)

[Jesssullivan]

Summary

• add a dispatch-only Homebrew fresh-install smoke workflow for the generated homebrew-tap formula
• install from the configured tap branch and run scripts/install-smoke.sh against installed tcfs/tcfsd
• capture Homebrew diagnostics as an artifact for the TIN-131/Prove distribution install and upgrade flows across supported release surfaces #280 distribution matrix

Validation

• ruby -ryaml load/shape check for the new workflow
• git diff --check

Refs: TIN-131, #280

[Jesssullivan]

Ready-for-review note:

• YAML parse and git diff --check are clean.
• I attempted to dispatch the new workflow from the branch, but GitHub Actions returned workflow not found on the default branch.
• That is expected for a brand-new workflow file; first live Homebrew smoke can run after this workflow lands on main.

Until then this PR proves workflow shape, not Homebrew first-use behavior.