fix: cap image sizes and increase memory limit to stop 502 crash loop

Next.js image optimization was generating 3840px images that caused the
container to exceed its 128MB memory limit, triggering repeated restarts.
Capped deviceSizes to max 1200px and bumped mem_limit to 256MB.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

docker-compose.yml

@@ -4,6 +4,7 @@ services:
     container_name: xhivart-mirror
     init: true
     restart: always
+    mem_limit: 256m
     environment:
       - SMTP_HOST=${SMTP_HOST}
       - SMTP_PORT=${SMTP_PORT}

next.config.ts

@@ -3,6 +3,8 @@ import type { NextConfig } from "next";
 const nextConfig: NextConfig = {
   output: "standalone",
   images: {
+    deviceSizes: [640, 750, 828, 1080, 1200],
+    imageSizes: [16, 32, 48, 64, 96, 128, 256, 384],
     localPatterns: [
       {
         pathname: "/images/**",