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/proxmox-datacenter-manager.json

@@ -0,0 +1,40 @@
+{
+  "name": "Proxmox Datacenter Manager (PDM)",
+  "slug": "proxmox-datacenter-manager",
+  "categories": [
+    1
+  ],
+  "date_created": "2024-12-25",
+  "type": "ct",
+  "updateable": true,
+  "privileged": false,
+  "interface_port": 8443,
+  "documentation": "https://pve.proxmox.com/wiki/Proxmox_Datacenter_Manager_Roadmap",
+  "website": "https://pve.proxmox.com/wiki/Proxmox_Datacenter_Manager_Roadmap",
+  "logo": "https://cdn.jsdelivr.net/gh/selfhst/icons@main/webp/proxmox.webp",
+  "config_path": "",
+  "description": "The Proxmox Datacenter Manager project has been developed with the objective of providing a centralized overview of all your individual nodes and clusters. It also enables basic management like migrations of virtual guests without any cluster network requirements. ",
+  "install_methods": [
+    {
+      "type": "default",
+      "script": "ct/proxmox-datacenter-manager.sh",
+      "resources": {
+        "cpu": 2,
+        "ram": 2048,
+        "hdd": 10,
+        "os": "debian",
+        "version": "13"
+      }
+    }
+  ],
+  "default_credentials": {
+    "username": null,
+    "password": null
+  },
+  "notes": [
+    {
+      "text": "Set a root password if using autologin. This will be the Proxmox-Datacenter-Manager password. `sudo passwd root`",
+      "type": "info"
+    }
+  ]
+}