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/exportUserRights.graphql

@@ -0,0 +1,28 @@
+# Source: https://www.zabbix.com/documentation/7.4/en/manual/api/reference/usergroup/get
+
+### Query
+```graphql
+query ExportUserRights($name_pattern: String) {
+  exportUserRights(name_pattern: $name_pattern) {
+    userGroups {
+      usrgrpid
+      name
+      hostgroup_rights {
+        name
+        permission
+      }
+    }
+    userRoles {
+      roleid
+      name
+    }
+  }
+}
+```
+
+### Variables
+```json
+{
+  "name_pattern": "Zabbix%"
+}
+```