feat(vscodex): add remote Codex collaboration module

aether-vscodex/Dockerfile

@@ -0,0 +1,26 @@
+FROM node:22-alpine
+
+ENV NODE_ENV=production \
+    HOST=0.0.0.0 \
+    PORT=8788 \
+    AETHER_VSCODEX_DATA_DIR=/var/lib/aether-vscodex
+
+WORKDIR /app
+
+COPY package.json package-lock.json ./
+RUN npm ci --omit=dev && npm cache clean --force
+
+COPY cloud ./cloud
+COPY relay ./relay
+COPY public ./public
+
+RUN mkdir -p /var/lib/aether-vscodex && chown -R node:node /var/lib/aether-vscodex /app
+
+USER node
+
+EXPOSE 8788
+
+HEALTHCHECK --interval=30s --timeout=5s --start-period=5s --retries=3 \
+  CMD node -e "fetch('http://127.0.0.1:8788/healthz').then(r=>{if(!r.ok)process.exit(1)}).catch(()=>process.exit(1))"
+
+CMD ["node", "cloud/server.js"]