Add scripts/meta/resolve/image/local.sh as SPOT for the local Docker
image tag (<repo-basename>/<distro>). Wire it into Makefile build
targets (IMAGE_TAG), compose.py (_base_env sets INFINITO_IMAGE), and
compose.yml (no default fallback). Fix build.sh to accept a pre-set
IMAGE_TAG without requiring REPO_PREFIX. Add make build + build-no-cache
to environment.sh test flow with correct section ordering.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>