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/umbrel-os-vm.json

@@ -0,0 +1,40 @@
+{
+  "name": "Umbrel OS",
+  "slug": "umbrel-os-vm",
+  "categories": [
+    2
+  ],
+  "date_created": "2025-05-28",
+  "type": "vm",
+  "updateable": true,
+  "privileged": false,
+  "interface_port": 80,
+  "documentation": "https://community.umbrel.com/c/guides/",
+  "website": "https://umbrel.com/",
+  "logo": "https://cdn.jsdelivr.net/gh/selfhst/icons@main/webp/umbrelos.webp",
+  "config_path": "",
+  "description": "Take control of your digital life with Umbrel — a private, personal server that lets you self-host powerful open source apps with ease. Whether you want to run a Bitcoin or Lightning node, manage your files with Nextcloud, stream media, block ads across your network, or explore self-hosted AI tools, Umbrel gives you full ownership and privacy. All through a beautiful, user-friendly interface — no cloud, no tracking, just your data under your control.",
+  "install_methods": [
+    {
+      "type": "default",
+      "script": "vm/umbrel-os-vm.sh",
+      "resources": {
+        "cpu": 2,
+        "ram": 4096,
+        "hdd": 32,
+        "os": "debian",
+        "version": "12"
+      }
+    }
+  ],
+  "default_credentials": {
+    "username": "umbrel",
+    "password": "umbrel"
+  },
+  "notes": [
+    {
+      "text": "This VM use as base a Debian 12 OS with a custom kernel and some additional packages to run Umbrel OS. It is not a standard Debian VM, but it is optimized for Umbrel OS.",
+      "type": "info"
+    }
+  ]
+}