fix: JCEF as default mode in bootstrap, JFX only with --jfx

launcher/bootstrap/src/main/java/me/sashegdev/zernmc/launcher/Bootstrap.java

@@ -56,13 +56,7 @@ public class Bootstrap {
         
         List<String> argList = new ArrayList<>(Arrays.asList(args));
         isCliMode = argList.contains("--cli") || (System.console() != null && !argList.contains("--jfx") && !argList.contains("--jcef"));
-        // Auto-detect UI backend: prefer JCEF, fall back to JavaFX
-        boolean javafxAvailable = false;
-        if (Files.exists(javafxPath)) {
-            try (var list = Files.list(javafxPath)) {
-                javafxAvailable = list.findAny().isPresent();
-            } catch (Exception ignored) {}
-        }
+        // Default: JCEF mode. JavaFX only with explicit --jfx flag.
         if (argList.contains("--jfx")) {
             isJfxMode = true;
             isJcefMode = false;
@@ -70,8 +64,8 @@ public class Bootstrap {
             isJfxMode = false;
             isJcefMode = true;
         } else {
-            isJfxMode = javafxAvailable;
-            isJcefMode = !javafxAvailable;
+            isJfxMode = false;
+            isJcefMode = true;
         }
         if (isCliMode && !argList.contains("--cli")) {
             argList.add("--cli");