Site: Update Snowflake vendor description (apache#15745)

Rewrite the Snowflake section to lead with Horizon Catalog, add DDL
support, Iceberg REST endpoint for external engines, catalog-linked
databases, and externally managed table write access. Use proper
Apache prefixes for engine names.

Author: manisin

site/docs/vendors.md

@@ -167,7 +167,7 @@ By directly reading and [managing](https://docs.singlestore.com/cloud/load-data/
 ### [Snowflake](https://snowflake.com/)
 
 <!-- markdown-link-check-disable-next-line -->
-[Snowflake](https://www.snowflake.com/) is a single, cross-cloud platform that enables every organization to mobilize their data with Snowflake’s Data Cloud. Snowflake supports Apache Iceberg by offering [Snowflake-managed Iceberg Tables](https://docs.snowflake.com/en/user-guide/tables-iceberg#use-snowflake-as-the-iceberg-catalog) for full DML as well as [externally managed Iceberg Tables with catalog integrations](https://docs.snowflake.com/en/user-guide/tables-iceberg#use-a-catalog-integration) for read-only access.
+[Snowflake](https://www.snowflake.com/) is a single, cross-cloud platform that enables every organization to mobilize their data with Snowflake’s Data Cloud. [Snowflake Horizon Catalog](https://docs.snowflake.com/en/user-guide/snowflake-horizon) is the universal catalog built into every Snowflake account, providing governance, metadata, and interoperability for Apache Iceberg across engines and clouds. Snowflake supports [Snowflake-managed Iceberg Tables](https://docs.snowflake.com/en/user-guide/tables-iceberg#use-snowflake-as-the-iceberg-catalog) with full DDL and DML support and an [Iceberg REST API endpoint](https://docs.snowflake.com/en/user-guide/tables-iceberg-access-using-external-query-engine-snowflake-horizon) that lets external query engines such as Apache Spark, Trino, and Apache Flink read and write those tables directly. For federation, [catalog-linked databases](https://docs.snowflake.com/en/user-guide/tables-iceberg-catalog-linked-database) provide automatic table discovery and synchronization with remote Iceberg REST catalogs, and read and write access through [catalog integrations for externally managed Iceberg Tables](https://docs.snowflake.com/en/user-guide/tables-iceberg#use-an-external-catalog).
 
 ### [Stackable](https://stackable.tech)