Added support for METADATA_SCHEMA in ducklake config.yml

[justbry]

Summary

Add support for the METADATA_SCHEMA configuration option for DuckLake catalogs in DuckDB connections. This allows
users to specify which schema in the catalog server should store DuckLake metadata tables.

Changes

• Core Configuration (sqlmesh/core/config/connection.py):
  • Added metadata_schema optional field to DuckDBAttachOptions
  • Updated to_sql() method to include METADATA_SCHEMA parameter in the DuckDB ATTACH statement when specified
• Documentation (docs/integrations/engines/duckdb.md):
  • Added metadata_schema to YAML and Python configuration examples for DuckLake catalogs
  • Added comprehensive configuration options table documenting all DuckLake-specific parameters including the new
    metadata_schema option
• Tests (tests/core/test_connection_config.py):
  • Added test_ducklake_metadata_schema() with three test cases:
    • Verifies METADATA_SCHEMA is included in SQL when specified
    • Confirms default behavior (no METADATA_SCHEMA) when not specified
    • Tests interaction with other DuckLake options (data_path, encrypted)

Motivation

DuckLake users need the ability to control where metadata tables are stored within the catalog server. The default
main schema may not always be appropriate for organizational or security requirements. This configuration option
provides that flexibility while maintaining backward compatibility (defaults to DuckLake's default behavior when not
specified).

Example Usage

gateways:
my_gateway:
connection:
type: duckdb
catalogs:
ducklake_catalog:
type: ducklake
path: catalog.ducklake
metadata_schema: custom_workspace

Test Plan

• Unit tests verify SQL generation with and without metadata_schema
• Unit tests confirm compatibility with other DuckLake options
• Documentation updated with examples

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[georgesittas]

Hey @justbry, thank you for the PR. Where is METADATA_SCHEMA documented?

[justbry]

METADATA_SCHEMA is documented in docs/integrations/engines/duckdb.md

https://github.com/TobikoData/sqlmesh/pull/5456/files#diff-de5de8bb701edca7af9847e114df48bfceefda5f991eaa196a2dfe765a5af9a3