fix: mover Dockerfile a nuxt4-app/ y corregir workflow

nuxt4-app/Dockerfile

@@ -0,0 +1,40 @@
+# Build stage
+FROM node:22-alpine AS builder
+
+WORKDIR /app
+
+# Install build dependencies for sharp
+RUN apk add --no-cache python3 make g++ vips-dev
+
+# Copy package files
+COPY nuxt4-app/package*.json ./
+
+# Install dependencies
+RUN npm install --prefer-offline --no-audit
+
+# Copy app source
+COPY nuxt4-app/ ./
+
+# Build the application
+RUN npm run build
+
+# Production stage
+FROM node:22-alpine
+
+WORKDIR /app
+
+# Install runtime dependencies for sharp
+RUN apk add --no-cache vips
+
+# Copy built application from builder
+COPY --from=builder /app/.output /app/.output
+
+# Expose port (internal, no published externally)
+EXPOSE 3000
+
+ENV NODE_ENV=production
+ENV HOST=0.0.0.0
+ENV PORT=3000
+
+# Start the application
+CMD ["node", ".output/server/index.mjs"]