feat: implement template cloning and extended item data retrieval

- Extend Template and ZabbixItem types in GraphQL schema to support full item hierarchy and cloning.

- Update ZabbixQueryTemplatesRequest in src/datasources/zabbix-templates.ts to fetch comprehensive item configurations (type, status, history, delay, units, preprocessing, tags).

- Implement raw value resolvers for ZabbixItem.type_int and ZabbixItem.status_int in src/api/resolvers.ts.

- Add new MCP operations: mcp/operations/getTemplates.graphql and mcp/operations/importTemplates.graphql for template management via AI agents.

- Add 'Cloning a Template with Items' recipe to docs/howtos/cookbook.md.

- Update src/test/template_query.test.ts to ensure compatibility with extended datasource output.

mcp/operations/getTemplates.graphql

@@ -0,0 +1,21 @@
+query GetTemplates($name_pattern: String) {
+  templates(name_pattern: $name_pattern) {
+    templateid
+    host
+    name
+    items {
+      name
+      key_
+      type
+      value_type
+      status
+      history
+      delay
+      units
+      description
+      preprocessing
+      tags
+      master_itemid
+    }
+  }
+}