[luthermonson]

CakePHP 5's schema reflection (describeForeignKeySql / describeCheckConstraints) queries information_schema.key_column_usage, referential_constraints, table_constraints and check_constraints. litewire didn't emulate them, so every table describe returned 1064 and the app 500'd.

What this adds

Four more emulated information_schema views, in the same derived-table style as the existing tables/columns/statistics/schemata emulation:

• key_column_usage — one row per foreign-key column, all 12 MySQL columns. Derived from pragma_foreign_key_list; primary/unique columns are not listed. An implicit REFERENCES t resolves to the parent's key column.
• referential_constraints — one row per FK, all 11 MySQL columns (incl. UPDATE_RULE/DELETE_RULE).
• table_constraints — primary keys and foreign keys (UNIQUE/CHECK not listed).
• check_constraints — always empty; SQLite keeps CHECK clauses only inside the CREATE text.

Unnamed SQLite FKs are named <table>_ibfk_<n>, matching MySQL's unnamed-InnoDB-key convention. constraint_schema and referenced_table_schema now fold like table_schema, so a bound schema name matches litewire's main.

Integer columns are CAST(... AS INTEGER): on Turso a prepared select of an integer expression through a derived table drops the connection unless the expression carries a declared type.

Tests

New mysql_infoschema_fk runs both CakePHP queries verbatim as prepared statements over the wire on rusqlite and Turso, plus plain SELECT * column-name checks, the empty case, FK rules (CASCADE/SET NULL), composite FKs, and table_constraints. clippy --all-targets -D warnings and nightly fmt are clean. (single_tenant_attach_keeps_working_over_the_wire fails identically on untouched main — a pre-existing Windows path issue.)

Verified end-to-end against the consolidated wun image: CakePHP's describe no longer 1064s and GET /api/products is byte-identical to the oracle.