Add Native App consumer quickstart

[osipovartem]

Summary

• add a consumer quickstart for installing the private Native App listing, creating a Snowflake-managed Iceberg smoke table, starting Rustice, and querying through embucket-snow
• add APP_PUBLIC.CONFIGURE_COMPUTE(instance_family, min_nodes, max_nodes, auto_suspend_secs) so consumers can choose the SPCS compute pool size before starting the app
• document Snowsight and Snowflake CLI paths, Horizon credential binding, endpoint testing, and cleanup

Verification

• snow app bundle succeeds for deploy/native-app

Notes

• consumer accounts must have External Access Integration support enabled; trial accounts can install the app but fail during CONFIGURE_EXTERNAL_ACCESS with Snowflake error: External access is not supported for trial accounts.