Fix PgBouncer dev auth: use plain auth_type for PostgreSQL 16 scram-sha-256

PostgreSQL 16 defaults to scram-sha-256, md5 hashes in userlist are
rejected. Using auth_type=plain in dev with plaintext password.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

docker/pgsql/pgbouncer-dev.ini

@@ -4,7 +4,7 @@ e_ticket = host=database port=5432 dbname=e_ticket
 [pgbouncer]
 listen_addr = 0.0.0.0
 listen_port = 6432
-auth_type = md5
+auth_type = plain
 auth_file = /etc/pgbouncer/userlist.txt
 pool_mode = transaction
 max_client_conn = 200

docker/pgsql/userlist-dev.txt

@@ -1 +1 @@
-"app" "md56a422f785c9e20873908ce25d1736ae2"
+"app" "secret"