feat: add Dockerfile for Coolify deployment (volumes support)

Dockerfile

@@ -0,0 +1,19 @@
+FROM node:20-alpine
+
+WORKDIR /app
+
+# Зависимости
+COPY package*.json ./
+RUN npm ci --omit=dev
+
+# Код
+COPY . .
+
+# Папка для uploads (будет примонтирована через volume)
+RUN mkdir -p /var/www/zeropost-uploads
+
+EXPOSE 3030
+ENV PORT=3030
+ENV NODE_ENV=production
+
+CMD ["node", "index.js"]