devlog v2.2.4

Homebrew moves to the shared aice-lab tap.

The formula is now published to aice-lab/homebrew-tap — the same tap that serves
envkit — instead of the personal ananno/homebrew-devlog namespace. One
`brew tap aice-lab/tap` now gets every aice-lab tool.

Install:
  brew tap aice-lab/tap https://gitlab.com/aice-lab/homebrew-tap.git
  brew install devlog

The old tap keeps working but stops being updated from this release on.
Homebrew is also documented in the README for the first time; it had been a
working but undocumented channel.

CI and docs only. No functional change to devlog.