chore: AAB/APK 출력 파일명에 variant, 버전, 타임스탬프 포함

- 형식: Runnect-{variant}-v{version}-{yyyyMMdd_HHmmss}.{aab|apk}
- 예시: Runnect-release-v2.2.0-20260403_173829.aab

Author: unam98

app/build.gradle

@@ -69,6 +69,15 @@ android {
         }
     }
 
+    applicationVariants.all { variant ->
+        variant.outputs.all {
+            def timestamp = new Date().format('yyyyMMdd_HHmmss')
+            def versionName = variant.versionName
+            def ext = outputFileName.endsWith('.aab') ? 'aab' : 'apk'
+            outputFileName = "Runnect-${variant.buildType.name}-v${versionName}-${timestamp}.${ext}"
+        }
+    }
+
     compileOptions {
         sourceCompatibility JavaVersion.VERSION_17
         targetCompatibility JavaVersion.VERSION_17