Fix replacement in attached Postgres catalogs

[clowrance-proppilot]

Description

DuckDB does not support CREATE OR REPLACE TABLE for tables in an attached Postgres catalog. SQLMesh currently selects replacement behavior using the current DuckDB catalog rather than the target table catalog, so a full refresh of an attached Postgres table attempts unsupported DDL. It also fails when the physical table has dependent SQLMesh virtual-layer views.

This change:

• detects catalog type from the target table catalog
• replaces attached Postgres tables with DROP TABLE IF EXISTS ... CASCADE followed by the normal create path
• adds a regression test for target-catalog lookup and generated replacement SQL

SQLMesh recreates the virtual-layer views after physical model evaluation, so cascading those dependencies matches the full-refresh lifecycle.

Related context:

• SQLMesh generates DROP TABLE for PostgreSQL views when using DuckDB engine #5438 tracks DuckDB/Postgres relation-type misclassification during virtual-layer promotion
• fix(duckdb): ensure drop_table handles views to avoid catalog errors #5695 and Fix: Fallback to DROP VIEW if DROP TABLE fails in DuckDB #5809 propose complementary fallbacks for dropping a Postgres view misreported as a table
• feat: add multiple catalogs functionality to MotherDuck connection  #3484 introduced attached-catalog support

This PR addresses physical table replacement in an attached Postgres catalog; it does not claim to close #5438 by itself.

Test Plan

• make style
• make fast-test
• pytest tests/core/engine_adapter/test_duckdb.py -q

Checklist

• I have run make style and fixed any issues
• I have added tests for my changes (if applicable)
• All existing tests pass (make fast-test)
• My commits are signed off (git commit -s) per the DCO