fix(entrypoint): restore server case (lost during doctor->check refactor)

Il caso 'server)' era stato eliminato inavvertitamente: CMD [server]
cadeva nel *) exec $@ -> 'server: not found' (exit 127).
Smoke standalone ora verde: health + config check + db ping (read-only).

docker/core-entrypoint.sh

@@ -7,6 +7,9 @@ export THT_CONFIG="${THT_CONFIG:-/app/harness/workspaces/local.yaml}"
 
 cmd="${1:-server}"
 case "$cmd" in
+  server)
+    exec node /app/backend/dist/server.js
+    ;;
   check)
     # Diagnostica di wiring: validazione config/env + ping DWH (read-only).
     shift