Refactor Dockerfile for multi-stage build and update start script in package.json

- Introduced a multi-stage build in the Dockerfile to separate build and runtime environments.
- Added environment variables for production in the runtime stage.
- Updated the start script in package.json to point to the new server entry point.

Dockerfile

@@ -1,11 +1,21 @@
-FROM node:22.12-bullseye
-
+# --- build stage ---
+FROM node:22.12-bullseye AS build
 WORKDIR /app
-
 COPY package.json yarn.lock ./
 RUN corepack enable && yarn install --frozen-lockfile
-
 COPY . .
 RUN yarn build
 
-CMD ["yarn", "start"]
+# --- runtime stage ---
+FROM node:22.12-bullseye AS runner
+WORKDIR /app
+ENV NODE_ENV=production \
+    NITRO_HOST=0.0.0.0 \
+    NITRO_PORT=3000 \
+    HOST=0.0.0.0 \
+    PORT=3000
+COPY --from=build /app/.output ./.output
+# (Optional) copy any public/static if you need it at runtime:
+# COPY --from=build /app/public ./public
+EXPOSE 3000
+CMD ["node", ".output/server/index.mjs"]

package.json

@@ -7,7 +7,8 @@
     "dev": "nuxt dev",
     "generate": "nuxt generate",
     "preview": "nuxt preview",
-    "postinstall": "nuxt prepare"
+    "postinstall": "nuxt prepare",
+    "start": "node .output/server/index.mjs"
   },
   "dependencies": {
     "mongodb": "^6.18.0",