chore: add tests for schema and API config mocking

- Added unit tests for schema loader, mocking Config variables and resolvers.
- Added unit tests for Zabbix API configuration, verifying constants derived from Config.
- Mocked relevant modules and filesystem behaviors to enable isolated testing.
- Optimized imports on all files and include this within a new .junie/guidelines.md file

src/datasources/zabbix-hosts.ts

@@ -9,7 +9,6 @@ import {
     ZabbixResult
 } from "./zabbix-request.js";
 import {ZabbixHistoryGetParams, ZabbixQueryHistoryRequest} from "./zabbix-history.js";
-import {isArray} from "node:util";
 
 
 export class ZabbixQueryHostsGenericRequest<T extends ZabbixResult, A extends ParsedArgs = ParsedArgs> extends ZabbixRequest<T, A> {