chore: add Nginx Dockerfile for Coolify production deployment

Dockerfile

@@ -0,0 +1,14 @@
+# Stage 1: Build Vite SPA
+FROM node:22-alpine AS build
+WORKDIR /app
+COPY package*.json ./
+RUN npm ci
+COPY . .
+RUN npm run build
+
+# Stage 2: Production Nginx Server
+FROM nginx:alpine
+COPY --from=build /app/dist /usr/share/nginx/html
+COPY --from=build /app/nginx.conf /etc/nginx/conf.d/default.conf
+EXPOSE 80
+CMD ["nginx", "-g", "daemon off;"]