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/backrest.json

@@ -0,0 +1,40 @@
+{
+  "name": "Backrest",
+  "slug": "backrest",
+  "categories": [
+    7
+  ],
+  "date_created": "2025-05-27",
+  "type": "ct",
+  "updateable": true,
+  "privileged": false,
+  "interface_port": 9898,
+  "documentation": "https://garethgeorge.github.io/backrest/introduction/getting-started",
+  "website": "https://garethgeorge.github.io/backrest",
+  "logo": "https://cdn.jsdelivr.net/gh/selfhst/icons@main/webp/backrest.webp",
+  "config_path": "/opt/backrest/config/config.json | /opt/backrest/.env",
+  "description": "Backrest is a web-accessible backup solution built on top of restic and providing a WebUI which wraps the restic CLI and makes it easy to create repos, browse snapshots, and restore files. Additionally, Backrest can run in the background and take an opinionated approach to scheduling snapshots and orchestrating repo health operations.",
+  "install_methods": [
+    {
+      "type": "default",
+      "script": "ct/backrest.sh",
+      "resources": {
+        "cpu": 1,
+        "ram": 512,
+        "hdd": 8,
+        "os": "debian",
+        "version": "13"
+      }
+    }
+  ],
+  "default_credentials": {
+    "username": null,
+    "password": null
+  },
+  "notes": [
+    {
+      "type": "info",
+      "text": "`cat ~/.ssh/id_ed25519.pub` to view ssh public key. This key is used to authenticate with sftp targets. You can add this key on the sftp server."
+    }
+  ]
+}