fix: create hades_user in dbinit for shared MySQL compatibility

Shared MySQL (mysql-5-7) only has mysql_user. The hades app connects
as hades_user which doesn't exist. dbinit runs as root, so it can
create the user before migrations run.

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

hades/sql/000_create_db.sql

@@ -2,3 +2,8 @@
 -- This file runs first to ensure proper migration ordering
 
 SELECT 'Database migration starting for hades_db' AS message;
+
+-- Create hades_user for app connections (shared MySQL only has mysql_user)
+CREATE USER IF NOT EXISTS 'hades_user'@'%' IDENTIFIED BY 'local-hades-pass';
+GRANT ALL PRIVILEGES ON hades_db.* TO 'hades_user'@'%';
+FLUSH PRIVILEGES;