refactor(nginx): single www volume with html/ subdirectory

- Removed separate html volume, use /var/www as single web root
- Moved html/ content into www/html/
- Updated default.conf root to /var/www/html
- Allows organizing multiple sites under /var/www (html, mon_site, etc.)

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

apps/nginx/docker-compose.json

@@ -19,10 +19,6 @@
           "hostPath": "${APP_DATA_DIR}/data/www",
           "containerPath": "/var/www"
         },
-        {
-          "hostPath": "${APP_DATA_DIR}/data/html",
-          "containerPath": "/usr/share/nginx/html"
-        },
         {
           "hostPath": "${APP_DATA_DIR}/data/logs",
           "containerPath": "/var/log/nginx"