fix(music): use white tab labels instead of default blue

The music library tab view did not set tabBarActiveTintColor/
tabBarInactiveTintColor, so React Navigation's material-top-tabs
fell back to its default blue active tint. Set explicit white
(active) and gray (inactive) tint colors.

app/(auth)/(tabs)/(libraries)/music/[libraryId]/_layout.tsx

@@ -40,6 +40,8 @@ const Layout = () => {
         keyboardDismissMode='none'
         screenOptions={{
           tabBarBounces: true,
+          tabBarActiveTintColor: "#FFFFFF",
+          tabBarInactiveTintColor: "#9CA3AF",
           tabBarLabelStyle: {
             fontSize: TAB_LABEL_FONT_SIZE,
             fontWeight: "600",