Make dropdown arrow white for better visibility on green button

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

app/src/main/res/drawable/ic_keyboard_arrow_down.xml

@@ -4,6 +4,6 @@
     android:viewportWidth="24"
     android:viewportHeight="24">
     <path
-        android:fillColor="#6750A4"
+        android:fillColor="#FFFFFF"
         android:pathData="M7.41,8.59L12,13.17l4.59,-4.58L18,10l-6,6 -6,-6z"/>
 </vector>