End-to-end database connection for agami: sets up credentials on first run (DB-type picker → writes <artifacts_dir>/local/credentials.example for the user to fill in), then introspects the live DB directly into the agami semantic model (subject areas, tables, columns, relationships with join cardina
End-to-end database connection for agami: sets up credentials on first run (DB-type picker → writes <artifacts_dir>/local/credentials.example for the user to fill in), then introspects the live DB directly into the agami semantic model (subject areas, tables, columns, relationships with join cardinality, deep-table column groups, sensitive-column flags) under <artifacts_dir>/<profile>/. The struct