fix: use lsn for text

Author: psteinroe

migrations/1767183702000_lsn_to_text.sql

@@ -0,0 +1,4 @@
+-- Change lsn column from pg_lsn to text to avoid ETL schema mismatch
+-- The ETL crate doesn't have pg_lsn in its type mappings, causing "schema has changed" errors
+alter table pgstream.events
+alter column lsn type text using lsn::text;