fix: use sql.NullString for apiClientIP in logs query

Change apiClientIP from string to sql.NullString to properly handle
NULL values from the database, preventing potential runtime errors
when the column contains NULL entries.

src/auth.go

@@ -302,8 +302,8 @@ func logsHandler(db *sql.DB) http.HandlerFunc {
 		logs := make([]map[string]interface{}, 0)
 		for rows.Next() {
 			var ts time.Time
-			var action, apiClientIP string
-			var ip, reason sql.NullString
+			var action string
+			var ip, reason, apiClientIP sql.NullString
 			var ttlSeconds sql.NullInt64
 			if err := rows.Scan(&ts, &action, &ip, &ttlSeconds, &reason, &apiClientIP); err != nil {
 				continue