feat(txt-game): initial module scaffold

Number guessing game (1-100, 7 attempts) as a HAL custom-app module.
Serves HTML form UI with per-session state via cookie, no npm deps.
Traefik labels for txt.${DOMAIN} on websecure with letsencrypt TLS.

Dockerfile

@@ -0,0 +1,9 @@
+FROM node:22-alpine
+
+WORKDIR /app
+
+COPY server.mjs ./
+
+EXPOSE 3000
+
+CMD ["node", "server.mjs"]