feat(banner): 배너 XML 레이아웃 속성을 추가한다

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

app/src/main/res/layout/item_banner.xml

@@ -0,0 +1,15 @@
+<?xml version="1.0" encoding="utf-8"?>
+<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    android:background="@drawable/bg_banner_preview_placeholder">
+
+    <ImageView
+        android:id="@+id/iv_banner"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        android:background="@drawable/bg_banner_preview_placeholder"
+        android:contentDescription="@null"
+        android:scaleType="centerCrop" />
+
+</FrameLayout>