Rename storage/ to appdata/ in all compose templates

Part of v0.14.0 storage architecture overhaul — standardize
app data paths under appdata/ instead of storage/.

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

templates/nextcloud/docker-compose.yml

@@ -35,7 +35,7 @@ services:
       - REDIS_HOST=nextcloud-redis
     volumes:
       - nextcloud_html:/var/www/html
-      - ${HDD_PATH}/storage/nextcloud:/var/www/html/data
+      - ${HDD_PATH}/appdata/nextcloud:/var/www/html/data
     networks:
       - traefik-public
       - nextcloud-internal