v0.48.1

The SDK's constraint/generated-column handling disagreed with the DuckDB
extension in both directions: tables with unattested non-null fields
failed to serve, records the extension refuses were served, 0.47 stored
catalog logs broke every listing, and clients could neither offer the
read profiles nor decode records.

• Nullability is relaxed, not policed: serving sets each field's Arrow
  nullability from the NOT_NULL/PRIMARY_KEY records (ordinary STRUCTs
  recursed, row id untouched). New constraints::served_columns and
  catalog::served_table_columns; every serve path goes through it.
• validate_table_constraints(schema_path, table, columns, records)
  now mirrors DecodeNativeConstraints: owner schema/table, one-component
  schema paths, duplicate ids and case-insensitive labels, one PRIMARY
  KEY, path resolution (nested only for NOT_NULL), same-schema
  MATCH SIMPLE NO_ACTION/RESTRICT foreign keys, size bounds, and the
  numeric-comparison CHECK grammar. validate_foreign_key_targets,
  CatSchema::validate_foreign_keys and CatalogModel::validate_tables
  check FK targets across a schema; listings and table_get run it.
• Generated columns follow ReadNativeColumnGenerated: nullable, Boolean/
  Int8..Int64/Utf8, default context, bounded grammar and operand types.
  Legacy generated_expression metadata is translated to the canonical
  pair when serving a catalog table instead of being rejected.
• StoredCatalog replays 0.47 logs carrying not_null/unique/check/
  primary_key by dropping the facts with a warning; constrained CREATE
  TABLE stays refused (no write path to enforce it) with an exact error.
• The record codec and capability helpers move to
  vgi_protocol::constraints (re-exported by vgi::constraints and
  vgi_client::constraints); new constraint_read_agreement for
  custom catalogs. vgi-client: AttachOptions.catalog_capabilities
  (default offers the constraint read profiles), table_constraints,
  AttachedCatalog::selected_capabilities.
• Legacy CatTable constraint fields, serialize_foreign_key and
  build_macro_arguments_schema are #[deprecated]; stale docs for
  CatMacro::parameter_docs and the vgi.v2-beside-v3 claim fixed.

Co-Authored-By: Claude Opus 5.5 noreply@anthropic.com