feat: optimize Zabbix queries and enhance specialized device support

- Implement query optimization (reduced output, parameter skipping) to minimize Zabbix API traffic.

- Add indirect dependency handling: deviceType implies tags and state implies items.

- Move schema extensions to samples/extensions/ to clarify their role as samples.

- Enhance DistanceTrackerDevice with String time fields to support optional date portions.

- Ensure allDevices strictly filters by deviceType and populates the field in results.

- Refactor runAllRegressionTests mutation to use internal unique names and improve stability.

- Fix unnecessary Zabbix API calls for item preprocessing during template and host imports.

- Update documentation including cookbook recipes, test specifications, and optimization guides.

- Add extensive unit, integration, and regression tests covering all implemented changes.

- Update docker-compose.yml to mount the samples/ directory as a volume.

- Update IntelliJ .idea run configurations to reflect the new sample extension paths.

samples/extensions/ground_value_checker.graphql

@@ -0,0 +1,46 @@
+"""
+GroundValueChecker represents a device that retrieves ground values
+from public APIs (e.g. BORIS NRW) using Zabbix HTTP agent items.
+"""
+type GroundValueChecker implements Host & Device {
+    """Internal Zabbix ID of the device."""
+    hostid: ID!
+    """
+    Per convention a uuid is used as hostname to identify devices if they do not have a unique hostname.
+    """
+    host: String!
+    """Classification of the device."""
+    deviceType: String
+    """List of host groups this device belongs to."""
+    hostgroups: [HostGroup!]
+    """Visible name of the device."""
+    name: String
+    """Device configuration tags."""
+    tags: DeviceConfig
+    """Host inventory data."""
+    inventory: Inventory
+    """List of monitored items for this host."""
+    items: [ZabbixItem!]
+    """State of the ground value checker device."""
+    state: GroundValueState
+}
+
+"""
+Represents the state of a ground value checker device.
+"""
+type GroundValueState implements DeviceState {
+    """Operational data (telemetry)."""
+    operational: OperationalDeviceData
+    """Current business values (ground data)."""
+    current: GroundValues
+}
+
+"""
+Aggregated ground information retrieved from the API.
+"""
+type GroundValues {
+    """
+    Average ground value (in €/m²). Extracted from the BORIS NRW GeoJSON response.
+    """
+    averageValue: Float
+}