refactor: Update method access modifiers per class and fix incorrect variable names

Author: ByteAurora

src/main/kotlin/com/github/ilovegamecoding/intellijcodexp/managers/CodeXPNotificationManager.kt

@@ -6,11 +6,11 @@ import com.intellij.notification.NotificationGroupManager
 import com.intellij.notification.NotificationType
 
 object CodeXPNotificationManager {
-    private val notifiationGroup: NotificationGroup =
+    private val notificationGroup: NotificationGroup =
         NotificationGroupManager.getInstance().getNotificationGroup("CodeXP")
 
-    fun notify(title: String, content: String) {
-        notifiationGroup.createNotification(title, content, NotificationType.INFORMATION).notify(null)
+    private fun notify(title: String, content: String) {
+        notificationGroup.createNotification(title, content, NotificationType.INFORMATION).notify(null)
     }
 
     fun notifyChallengeComplete(codeXPChallenge: CodeXPChallenge) {

src/main/kotlin/com/github/ilovegamecoding/intellijcodexp/services/CodeXPService.kt

@@ -158,7 +158,7 @@ class CodeXPService : PersistentStateComponent<CodeXPService.CodeXPState>, CodeX
      *
      * @param initializeCallback The callback to execute when the plugin is initialized.
      */
-    fun initialize(initializeCallback: () -> Unit) {
+    private fun initialize(initializeCallback: () -> Unit) {
         if (!codeXPState.hasExecuted) {
             initializeCallback()
             codeXPState.hasExecuted = true
@@ -180,7 +180,7 @@ class CodeXPService : PersistentStateComponent<CodeXPService.CodeXPState>, CodeX
      *
      * @param challenge The challenge to add.
      */
-    fun addChallenge(challenge: CodeXPChallenge) {
+    private fun addChallenge(challenge: CodeXPChallenge) {
         if (!codeXPState.challenges.containsKey(challenge.event)) {
             codeXPState.challenges[challenge.event] = challenge
         }