Implement splash screen functionality

Adds a splash screen to improve the app's initial loading experience.

android/app/build.gradle

@@ -1,3 +1,4 @@
+
 apply plugin: 'com.android.application'
 
 android {
@@ -49,6 +50,9 @@ dependencies {
     androidTestImplementation "androidx.test.ext:junit:$androidxJunitVersion"
     androidTestImplementation "androidx.test.espresso:espresso-core:$androidxEspressoCoreVersion"
     implementation project(':capacitor-cordova-android-plugins')
+    
+    // 스플래시 화면 플러그인 추가
+    implementation "androidx.core:core-splashscreen:1.0.0"
 }
 
 apply from: 'capacitor.build.gradle'