Match the deploy system to hops and greatbear

menu-admin was the odd one out: it built from the working directory with a date
tag and a multi-arch manifest, deployed with `-e tag=`, and kept the Docker-era
container name. The other two apps build from `git archive HEAD` and tag with the
commit, so what runs on the host is exactly what git knows about; build only for
the architecture emily actually runs; and use one slug for the container, its
network and its data directory.

The build is now their three lines: `podman build --platform linux/arm64` from
`git archive HEAD`, tagged `:<commit>` and `:latest`, pushed with `podman push`
rather than a manifest. `deploy.sh` pushes the commit first, then refuses a dirty
tracked tree or a HEAD that is not origin/main — which is what makes the commit
tag trustworthy — takes the same `--force` and `--no-push`, and ends in the same
`-u tanshu ... -e image_tag=<commit>`. Its own lint/typecheck/test gate stays,
but behind `--checks`, so a plain deploy behaves as theirs does.

The registry credential moves into vars/default.yml and the role logs in, pulls
and logs out around it, as their roles do. The image is only pulled at deploy
time, so the unit keeps podman's default `Pull=missing` and a reboot never needs
the registry. This is the same plaintext credential the other two repos carry.

One real bug goes with it: the healthcheck gate ran before the handler that
restarts a changed unit, so a run that only changed the unit checked the stale
container. `meta: flush_handlers` before the gate is the fix the sibling repos
already made.

The container, network and data directory are all menu-<site> now. The dotted
Docker-era name and the NetworkAlias it needed are gone, so `podman logs
menu-<site>` and `systemctl --user status menu-<site>` are the same two commands
across all three apps. The Dockerfile keeps its name for the same reason: podman
reads it as readily as a Containerfile, and the siblings use that name too.

compose.yaml

@@ -4,7 +4,7 @@
 #   npm run seed && podman compose up --build
 #
 # `podman compose` needs a provider on PATH — podman-compose or docker-compose.
-# The image is built from the Containerfile beside this file.
+# The image is built from the Dockerfile beside this file.
 services:
   menu:
     build: .