v3.2.2

Refactor — schema is the interface contract, not a demo artifact

Renames quicksight_gen/demo/schema.sql → quicksight_gen/schema.sql and the helper module quicksight_gen.demo → quicksight_gen.schema. The DDL is what production ETL writes against; the "demo" namespace was a misleading hangover from when the file lived under a top-level demo/ directory beside the seed generators. The quicksight-gen demo schema CLI command is unchanged. Importers should switch from from quicksight_gen.demo import generate_schema_sql to from quicksight_gen.schema import generate_schema_sql.