implement P4 lakehouse: deploy, load, and validate Iceberg tables (fix #14, fix #15, fix #16, fix #17)
- src/aco/lake/deploy.py: deploy_schemas() creates Iceberg namespaces
and tables from SQLTable models via PyIceberg REST Catalog
- src/aco/lake/load.py: load_to_iceberg() copies DuckDB tables to
Iceberg with append/replace modes
- src/cli/lake.py: wire deploy, load, validate commands with
--catalog-type (nessie/polaris), --schema, --dry-run, --mode options
- Catalog.validate() compares SQLTable definitions vs Iceberg metadata
- 20 new tests (type resolution, dry run, mock deploy/load, CLI help)
- All 11339 tests pass
4f67b4f9fd
