heliosdb-nano-schema

Define and inspect schema in HeliosDB-Nano. Covers CREATE/ALTER/DROP TABLE with PK/FK/UNIQUE/CHECK/DEFAULT constraints, regular and HNSW vector indexes, views, materialized views, stored procedures, and introspection through Postgres (pg_class, information_schema), SQLite (sqlite_master, PRAGMA table_info), and Nano-specific (\d, \dt, \dS, \dmv) surfaces. Also documents why CREATE TRIGGER succeeds but trigger bodies…