feat: add container file

- update README.md for containerization

Containerfile

@@ -0,0 +1,22 @@
+# Stage 1: Build
+FROM node:20-alpine AS builder
+WORKDIR /app
+COPY package*.json ./
+RUN npm ci
+COPY . .
+RUN npm run build
+RUN npm prune --production
+
+# Stage 2: Run
+FROM node:20-alpine
+WORKDIR /app
+COPY --from=builder /app/build ./build
+COPY --from=builder /app/node_modules ./node_modules
+COPY package.json .
+
+# Default SvelteKit production port
+ENV PORT=3000
+EXPOSE 3000
+
+# Start the app
+CMD ["node", "build"]