feat: Add Dockerfile for multi-stage Node.js build with Nginx and .dockerignore.

Dockerfile

@@ -0,0 +1,19 @@
+# Stage 1: Build
+FROM node:20-alpine AS builder
+
+WORKDIR /app
+
+COPY package*.json ./
+RUN npm install
+
+COPY . .
+RUN npm run build
+
+# Stage 2: Serve
+FROM nginx:alpine
+
+COPY --from=builder /app/dist /usr/share/nginx/html
+
+EXPOSE 80
+
+CMD ["nginx", "-g", "daemon off;"]