feat: plugin skeleton for Shopware 6.6 and 6.7 with CI and release pipeline

- composer.json (MIT, shopware/core ~6.6.0 || ~6.7.0, PHP ^8.2), plugin class, placeholder icon
- PR checks and release workflow taken over from AeonDumpManager; phpunit runs as a 6.6/6.7 matrix
- CHANGELOG, LICENSE, README, CLAUDE.md, smoke test

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docker-compose.yml

@@ -0,0 +1,31 @@
+services:
+  shopware:
+    image: dockware/shopware:6.7.14.2
+    container_name: shopware
+    ports:
+      - "80:80"       # Shop / Admin / Adminer / Mailcatcher (all served via path on this port)
+      - "443:443"     # HTTPS
+      #- "3306:3306"   # MySQL (exposed for external DB clients, e.g. TablePlus/DBeaver)
+      - "22:22"       # SSH into the container
+      - "8888:8888"   # Admin watcher (bin/build-administration.sh --watch)
+      - "9998:9998"   # Storefront watcher proxy
+      - "9999:9999"   # Storefront watcher
+    volumes:
+      - "db_volume:/var/lib/mysql"
+      - "shop_volume:/var/www/html"
+      - "./:/var/www/html/custom/plugins/AeonShopwareTools"
+    networks:
+      - web
+    environment:
+      - PHP_VERSION=8.3
+      - XDEBUG_ENABLED=1
+      - SW_CURRENCY=EUR
+      - SSH_USER=shopware
+      - SSH_PWD=shopware
+
+volumes:
+  db_volume:
+  shop_volume:
+
+networks:
+  web: