feat(demo): add read-only demo dockerfile and nginx api mocking.

Dockerfile.demo

@@ -0,0 +1,30 @@
+# Build arguments
+ARG NODE_VERSION=20
+ARG NODE_ALPINE_SHA256=sha256:6a91081a440be0b57336fbc4ee87f3dab1a2fd6f80cdb355dcf960e13bda3b59
+
+# Build the frontend
+FROM node:${NODE_VERSION}-alpine@${NODE_ALPINE_SHA256} AS build-frontend
+
+WORKDIR /src
+
+COPY package.json vite.config.js pnpm-lock.yaml tailwind.config.js postcss.config.js ./
+COPY meshchatx ./meshchatx
+
+RUN corepack enable && corepack prepare pnpm@latest --activate
+
+RUN pnpm install
+
+RUN pnpm run build-frontend
+
+RUN find /src/meshchatx/public -type d -exec chmod 755 {} + && \
+    find /src/meshchatx/public -type f -exec chmod 644 {} +
+
+# Runtime stage
+FROM nginxinc/nginx-unprivileged:alpine
+
+COPY --from=build-frontend --chown=101:101 /src/meshchatx/public /usr/share/nginx/html
+COPY nginx.demo.conf /etc/nginx/conf.d/default.conf
+
+EXPOSE 8080
+
+CMD ["nginx", "-g", "daemon off;"]