chore(android): 패키지명 변경 및 빌드 설정 업데이트

- 패키지명 com.example → com.naturebridgeai로 변경
- 기존 MainActivity.kt 삭제
- 새 패키지 경로에 MainActivity.kt 추가

android/app/build.gradle.kts

@@ -6,7 +6,7 @@ plugins {
 }
 
 android {
-    namespace = "com.example.asciineverdie"
+    namespace = "com.naturebridgeai.asciineverdie"
     compileSdk = flutter.compileSdkVersion
     ndkVersion = flutter.ndkVersion
 
@@ -21,7 +21,7 @@ android {
 
     defaultConfig {
         // TODO: Specify your own unique Application ID (https://developer.android.com/studio/build/application-id.html).
-        applicationId = "com.example.asciineverdie"
+        applicationId = "com.naturebridgeai.asciineverdie"
         // You can update the following values to match your application needs.
         // For more information, see: https://flutter.dev/to/review-gradle-config.
         minSdk = flutter.minSdkVersion

android/app/src/main/kotlin/com/naturebridgeai/asciineverdie/MainActivity.kt

@@ -1,4 +1,4 @@
-package com.example.asciineverdie
+package com.naturebridgeai.asciineverdie
 
 import io.flutter.embedding.android.FlutterActivity