Add rules language support and improve password validation across the app

db.go

@@ -91,6 +91,7 @@ func migrate() error {
 	// Idempotent column additions for older databases.
 	addColumns := []string{
 		`ALTER TABLE users ADD COLUMN must_change_password INTEGER NOT NULL DEFAULT 0`,
+		`ALTER TABLE competitions ADD COLUMN rules_language TEXT NOT NULL DEFAULT 'en'`,
 	}
 	for _, s := range addColumns {
 		// Ignore "duplicate column" errors so the migration is idempotent.