show the DEV badge on source-build dev stacks

The base compose file is the wilm/dev-be source build; stable and edge ship through the pull/airgap files. A raw source build is never a release, so default SHOPDB_ENV_LABEL to DEV here while leaving it overridable from .env.

docker-compose.yml

@@ -63,6 +63,11 @@ services:
       ZABBIX_TOKEN: ${ZABBIX_TOKEN:-}
       COLLECTOR_API_KEY: ${COLLECTOR_API_KEY:-}
       COLLECTOR_API_KEY_ENDPOINTS: ${COLLECTOR_API_KEY_ENDPOINTS:-}
+      # This file is the source-build dev stack (wilm/dev-be); stable and edge
+      # ship through the pull/airgap compose files, not this one. So default the
+      # badge label to DEV here - a raw source build is by definition not a
+      # release - while still allowing an override from .env.
+      SHOPDB_ENV_LABEL: ${SHOPDB_ENV_LABEL:-DEV}
     ports:
       - "${API_PORT:-5001}:5001"
     # Terminate TLS in gunicorn with the mounted self-signed cert so the browser