feat: add GroundValueChecker and WeatherSensorDevice with public API integration

This commit introduces two new device types, GroundValueChecker and WeatherSensorDevice, which leverage public APIs (BORIS NRW and Open-Meteo) for real-time data collection. It also includes several API enhancements and fixes to support these new integrations.

Detailed changes:
- **New Device Types**:
  - Added GroundValueChecker schema and integration with BORIS NRW WMS via Zabbix Script items.
  - Added WeatherSensorDevice schema and integration with Open-Meteo via Zabbix HTTP Agent items.
- **API Enhancements**:
  - Added error field to ZabbixItem for item-level error reporting.
  - Updated CreateTemplateItem mutation input to support params (for Script items) and timeout.
  - Registered missing scalar resolvers: JSONObject, DateTime, and Time.
- **Performance & Reliability**:
  - Implemented batch fetching for item preprocessing in both host and template queries to reduce Zabbix API calls and ensure data visibility.
  - Updated template_importer.ts to correctly handle Script item parameters.
- **Documentation**:
  - Consolidated public API device recipes in docs/howtos/cookbook.md.
  - Added guidance on analyzing data update frequency and setting reasonable update intervals (e.g., 1h for weather, 1d for ground values).
- **Testing**:
  - Added new regression test REG-ITEM-META to verify item metadata (units, description, error, preprocessing) and JSONObject scalar support.
  - Enhanced RegressionTestExecutor with more detailed host-item relationship verification.

schema/extensions/weather_sensor.graphql

@@ -40,11 +40,11 @@ Aggregated weather information retrieved from the API.
 """
 type WeatherSensorValues {
     """
-    Current temperature at the device location (in Celsius).
+    Current temperature at the device location (in °C).
     """
     temperature: Float
     """
-    Warnings or description of the street conditions (e.g. Ice, Rain, Clear).
+    Warnings or description of the street conditions (e.g. Ice, Rain, Clear). Derived from Open-Meteo weather codes.
     """
     streetConditionWarnings: String
 }