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/openproject.json

@@ -0,0 +1,40 @@
+{
+  "name": "OpenProject",
+  "slug": "openproject",
+  "categories": [
+    25
+  ],
+  "date_created": "2025-04-10",
+  "type": "ct",
+  "updateable": true,
+  "privileged": false,
+  "interface_port": 80,
+  "documentation": "https://www.openproject.org",
+  "website": "https://www.openproject.org",
+  "logo": "https://cdn.jsdelivr.net/gh/selfhst/icons@main/webp/openproject.webp",
+  "config_path": "/etc/openproject/conf.d/env",
+  "description": "OpenProject is a web-based project management software. Use OpenProject to manage your projects, tasks and goals. Collaborate via work packages and link them to your pull requests on Github. Read more about the OpenProject GitHub integration.",
+  "install_methods": [
+    {
+      "type": "default",
+      "script": "ct/openproject.sh",
+      "resources": {
+        "cpu": 2,
+        "ram": 4096,
+        "hdd": 8,
+        "os": "Debian",
+        "version": "13"
+      }
+    }
+  ],
+  "default_credentials": {
+    "username": "admin",
+    "password": "admin"
+  },
+  "notes": [
+    {
+      "text": "If you want to update from v15.x to v17.x, please read `https://www.openproject.org/docs/installation-and-operations/operation/upgrading/#major-upgrades` before doing so.",
+      "type": "warning"
+    }
+  ]
+}