fix: Use %server_max_players% and add fallback placeholders in GamingCore expansion

src/main/java/fr/luc/gamingcore/hook/GamingCorePlaceholderExpansion.java

@@ -56,6 +56,14 @@ public class GamingCorePlaceholderExpansion extends PlaceholderExpansion {
             return "";
         }
 
+        // Placeholders de serveur globaux
+        if (params.equalsIgnoreCase("max_players") || params.equalsIgnoreCase("maxplayers")) {
+            return String.valueOf(plugin.getServer().getMaxPlayers());
+        }
+        if (params.equalsIgnoreCase("online") || params.equalsIgnoreCase("online_players")) {
+            return String.valueOf(plugin.getServer().getOnlinePlayers().size());
+        }
+
         Guild guild = guildManager.getGuildByPlayer(player.getUniqueId());
 
         // Placeholders de vérification