Fix Dockerfile - use Node.js 22 instead of 20 for Astro 6 compatibility

Dockerfile

@@ -1,11 +1,11 @@
-FROM node:20-alpine AS builder
+FROM node:22-alpine AS builder
 WORKDIR /app
 COPY package*.json ./
 RUN npm install --legacy-peer-deps
 COPY . .
 RUN npm run build
 
-FROM node:20-alpine
+FROM node:22-alpine
 WORKDIR /app
 COPY package*.json ./
 RUN npm install --legacy-peer-deps