feat: add Zabbix 7.4 documentation samples and importHostGroups MCP tool

This commit introduces a comprehensive set of GraphQL query and mutation samples based on the official Zabbix 7.4 API documentation, along with testing and automation improvements.

Changes:

- Documentation:

  - Added 21 GraphQL sample files in docs/queries/from_zabbix_docs/ covering various Zabbix API operations.

  - Updated docs/howtos/cookbook.md with a new recipe for executing these documentation samples.

- AI & MCP:

  - Added mcp/operations/importHostGroups.graphql to enable host group import via MCP tools.

- Testing:

  - Added src/test/zabbix_docs_samples.test.ts to automatically validate all documentation samples against the GraphQL schema.

docs/queries/from_zabbix_docs/importHostGroups.graphql

@@ -0,0 +1,26 @@
+# Source: https://www.zabbix.com/documentation/7.4/en/manual/api/reference/hostgroup/create
+
+### Query
+```graphql
+mutation ImportHostGroups($hostGroups: [CreateHostGroup!]!) {
+  importHostGroups(hostGroups: $hostGroups) {
+    groupName
+    groupid
+    message
+  }
+}
+```
+
+### Variables
+```json
+{
+  "hostGroups": [
+    {
+      "groupName": "New Host Group 1"
+    },
+    {
+      "groupName": "New Host Group 2"
+    }
+  ]
+}
+```