Delete shelfmark (ct) after migration to ProxmoxVE (#1382)

Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

frontend/public/json/shelfmark.json

@@ -1,40 +0,0 @@
-{
-  "name": "Shelfmark",
-  "slug": "shelfmark",
-  "categories": [
-    13
-  ],
-  "date_created": "2026-01-24",
-  "type": "ct",
-  "updateable": true,
-  "privileged": false,
-  "interface_port": 8084,
-  "documentation": "https://github.com/calibrain/shelfmark/tree/main/docs",
-  "website": "https://github.com/calibrain/shelfmark",
-  "logo": "https://cdn.jsdelivr.net/gh/selfhst/icons@main/webp/shelfmark.webp",
-  "config_path": "/etc/shelfmark",
-  "description": "Shelfmark is a unified web interface for searching and aggregating books and audiobook downloads from multiple sources - all in one place.",
-  "install_methods": [
-    {
-      "type": "default",
-      "script": "ct/shelfmark.sh",
-      "resources": {
-        "cpu": 2,
-        "ram": 2048,
-        "hdd": 6,
-        "os": "Debian",
-        "version": "13"
-      }
-    }
-  ],
-  "default_credentials": {
-    "username": null,
-    "password": null
-  },
-  "notes": [
-    {
-      "text": "The configuration at `/etc/shelfmark/.env` is for bootstrapping the initial install. Customize the configuration via the Shelfmark UI.",
-      "type": "info"
-    }
-  ]
-}