fix: ensure skins directory existence and update infrastructure

- Create SKINS_DIR on startup to prevent upload errors\n- Add cdn_skins volume to docker-compose for persistence and Caddy serving\n- Update watchtower image to nickfedor/watchtower for Docker API compatibility\n\nCo-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

docker-compose.yml

@@ -15,6 +15,7 @@ services:
       - caddy_data:/data
       - caddy_config:/config
       - cdn_files:/var/www/cdn/files:ro
+      - cdn_skins:/var/www/cdn/skins:ro
 
   backend:
     image: gitea.mrixs.me/mrixs/mrixscraft-server:latest
@@ -30,6 +31,7 @@ services:
       BASE_URL: https://minecraft.mrixs.me
     volumes:
       - cdn_files:/var/www/cdn/files
+      - cdn_skins:/var/www/cdn/skins
     depends_on:
       postgres:
         condition: service_healthy
@@ -59,7 +61,7 @@ services:
       - "5432"
 
   watchtower:
-    image: containrrr/watchtower
+    image: nickfedor/watchtower
     container_name: mc-watchtower
     restart: unless-stopped
     volumes:
@@ -74,6 +76,8 @@ volumes:
     driver: local
   cdn_files:
     driver: local
+  cdn_skins:
+    driver: local
   caddy_data:
     driver: local
   caddy_config: