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 a Snowflake CLI preflight for fresh accounts where the default warehouse may not exist yet
• 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
• consumer clean-run verified on IFSMGKM-UIC40916 through:
  • private listing visibility and readiness
  • CREATE APPLICATION RUSTICE_NATIVE_APP FROM LISTING GZT1Z1J2YGM
  • requested app privileges granted
  • RUSTICE_SPCS.PUBLIC.SMOKE Snowflake-managed Iceberg table created and queried through Snowflake CLI
• CONFIGURE_EXTERNAL_ACCESS is currently blocked on that test consumer account by Snowflake account state:
  • 509009: External access is not supported for trial accounts

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.
• the currently published listing installs V0_1 patch 0, which does not yet include CONFIGURE_COMPUTE; that procedure becomes available after this PR is merged and a new Native App version/patch is published.