chore(frontend+infra): re-enable browser environment for Kotlin JS with NodeJs workaround

- Applied Root NodeJs plugin initialization to resolve Gradle 9/KMP race condition.
- Restored `browser {}` configuration in multiple frontend modules, with JS test tasks disabled to prevent redundant execution.

frontend/core/sync/build.gradle.kts

@@ -7,7 +7,12 @@ kotlin {
   jvm()
   js(IR) {
     binaries.library()
-    // browser {} block removed to fix "Plugin loaded multiple times" error.
+    // Re-enabled browser environment after Root NodeJs fix
+    browser {
+        testTask {
+            enabled = false
+        }
+    }
   }
 
   sourceSets {