feat(db): add incremental upsert seed script for WordNet vocabulary

Implements packages/db/src/seed.ts — reads all JSON files from
scripts/datafiles/, validates filenames against supported language
codes and POS, and upserts synsets into  and
via onConflictDoNothing. Safe to re-run; produces 0 writes on
a duplicate run.

packages/db/src/db/schema.ts

@@ -74,7 +74,6 @@ export const term_glosses = pgTable(
       table.language_code,
       table.text,
     ),
-    ,
     index("idx_term_glosses_term").on(table.term_id),
   ],
 );