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/execute.json

@@ -0,0 +1,48 @@
+{
+  "name": "PVE LXC Execute Command",
+  "slug": "execute",
+  "categories": [
+    1
+  ],
+  "date_created": "2025-09-18",
+  "type": "pve",
+  "updateable": false,
+  "privileged": false,
+  "interface_port": null,
+  "documentation": null,
+  "website": null,
+  "logo": "https://cdn.jsdelivr.net/gh/selfhst/icons@main/webp/proxmox.webp",
+  "config_path": "",
+  "description": "This script allows administrators to execute a custom command inside one or multiple LXC containers on a Proxmox VE node. Containers can be selectively excluded via an interactive checklist. If a container is stopped, the script will automatically start it, run the command, and then shut it down again. Only Debian and Ubuntu based containers are supported.",
+  "install_methods": [
+    {
+      "type": "default",
+      "script": "tools/pve/execute.sh",
+      "resources": {
+        "cpu": null,
+        "ram": null,
+        "hdd": null,
+        "os": null,
+        "version": null
+      }
+    }
+  ],
+  "default_credentials": {
+    "username": null,
+    "password": null
+  },
+  "notes": [
+    {
+      "text": "Execute within the Proxmox shell.",
+      "type": "info"
+    },
+    {
+      "text": "Non-Debian/Ubuntu containers will be skipped automatically.",
+      "type": "info"
+    },
+    {
+      "text": "Stopped containers will be started temporarily to run the command, then shut down again.",
+      "type": "warning"
+    }
+  ]
+}