refactor: remove frontend, move JSONs to json/ top-level

- Archive frontend to community-scripts/ProxmoxVE-Frontend-Archive
- Move frontend/public/json/ -> json/
- Update workflow paths in 5 actions:
  - update-versions-github.yml
  - update-json-date.yml
  - push-json-to-pocketbase.yml
  - delete-pocketbase-entry-on-removal.yml
  - autolabeler.yml
- Remove frontend-cicd.yml (no longer needed)
- Clean up .gitignore (remove frontend-specific entries)

json/webmin.json

@@ -0,0 +1,40 @@
+{
+  "name": "Webmin System Administration",
+  "slug": "webmin",
+  "categories": [
+    1
+  ],
+  "date_created": "2024-05-02",
+  "type": "addon",
+  "updateable": false,
+  "privileged": false,
+  "interface_port": 10000,
+  "documentation": "https://webmin.com/docs/",
+  "website": "https://webmin.com/",
+  "logo": "https://cdn.jsdelivr.net/gh/selfhst/icons@main/webp/webmin.webp",
+  "config_path": "",
+  "description": "Webmin provides a graphical user interface (GUI) for tasks such as user account management, package management, file system configuration, network configuration, and more.",
+  "install_methods": [
+    {
+      "type": "default",
+      "script": "tools/addon/webmin.sh",
+      "resources": {
+        "cpu": null,
+        "ram": null,
+        "hdd": null,
+        "os": null,
+        "version": null
+      }
+    }
+  ],
+  "default_credentials": {
+    "username": "root",
+    "password": "root"
+  },
+  "notes": [
+    {
+      "text": "Execute within an existing LXC Console",
+      "type": "info"
+    }
+  ]
+}