Public placeholder release

Build ./cmd/home-placeholder for the existing public skeleton at home.bds.oncarlos.com (including its aliases). It serves the same placeholder page and Oficina icons without opening a database or loading secrets. Activation may supply --db; this command deliberately ignores it.

The paired credential/directory deployments continue to use ./cmd/home. Do not deploy that binary onto the old public skeleton until its database and identity/domain migration have been planned and accepted. The old skeleton's Litestream-only database cannot be adopted by the current identity migrations.

Stamp the release with the source commit in amadan.net/rastrillo/rastrillo.BuildVersion, as for the main Home binary.

CGO_ENABLED=0 GOOS=linux GOARCH=arm64 go build -trimpath \
  -ldflags "-s -w -X amadan.net/rastrillo/rastrillo.BuildVersion=$(git rev-parse --short HEAD)" \
  -o /tmp/home-placeholder ./cmd/home-placeholder

Run Home's full make test gate on Linux with the checkout on ext4 or XFS. The provisioner is Linux-only and deliberately refuses overlayfs, Btrfs, and host-shared filesystems, including ordinary Docker bind mounts on macOS. A fresh runner also needs access to the pinned private Estilo Go module, or its verified Go download cache, before starting the gate.