DuckDB bugbash: `table_function` materialization parity

## Goal
Compare dbt Core `dbt-duckdb` vs dbt Fusion DuckDB behavior for `table_function` materialization.

## Experiment
Create a minimal documented-style `table_function` example and compare compile/run behavior between engines.

## Why this matters
This is a powerful DuckDB-specific adapter feature that could expose parity gaps.

## Success criteria
- Equivalent table-function materialization works in both engines, or
- a minimal repro isolates the Fusion gap

## Notes
Exclude static-analysis / `SQL_understanding` concerns from scope.