Get available query options for nodes

Returns available filters and sorting options for querying nodes. Sorting fields include verificationCheck and the deprecated integrityCheck alias for backward compatibility. Filter options may be simple strings (e.g., health statuses) or hierarchical objects (e.g., compute zones with nested nodegroups). Filter options examples: - Simple strings: `{"name": "healthStatuses", "options": ["Healthy", "Degraded", "Unhealthy"]}` - Hierarchical objects: `{"name": "computeZones", "options": [{"id": "cz-1", "value": "Zone 1", "options": [{"id": "ng-1", "value": "Node Group 1"}]}]}` The available options depend on the agentType view. The OOB view omits the gpuTypes filter and the GPU/kernel/driver/firmware/agentVersion sort fields, which apply only to in-band-enrolled nodes.