- Added comprehensive descriptions to all types, interfaces, and fields in 'schema/api_commons.graphql'.
- Improved documentation for mutations and input/response types in 'schema/mutations.graphql'.
- Added detailed descriptions for all queries and their arguments in 'schema/queries.graphql'.
- Enhanced documentation for core Zabbix types and enums in 'schema/zabbix.graphql'.
- Updated extension schemas under 'schema/extensions/' with proper GraphQL descriptions.
- Verified schema validity via 'graphql-codegen' and ran all tests to ensure consistency.
