[优化] 引导增加选择保存书籍文件夹

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

@@ -0,0 +1,61 @@
+<?xml version="1.0" encoding="utf-8"?>
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    android:orientation="vertical"
+    android:paddingHorizontal="16dp">
+
+    <TextView
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:text="@string/welcome_book_folder_tip"
+        android:textColor="?attr/colorOnSurfaceVariant"
+        android:textSize="14sp" />
+
+    <com.google.android.material.card.MaterialCardView
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:layout_marginTop="12dp"
+        app:cardBackgroundColor="?attr/colorSurfaceContainerLow"
+        app:cardCornerRadius="16dp"
+        app:cardElevation="0dp"
+        app:strokeColor="?attr/colorOutlineVariant"
+        app:strokeWidth="1dp">
+
+        <LinearLayout
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:orientation="vertical"
+            android:padding="14dp">
+
+            <TextView
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:text="@string/select_book_folder"
+                android:textColor="?attr/colorOnSurface"
+                android:textStyle="bold" />
+
+            <TextView
+                android:id="@+id/tvFolderPath"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:layout_marginTop="8dp"
+                android:maxLines="3"
+                android:textColor="?attr/colorOnSurfaceVariant"
+                android:textSize="13sp" />
+
+            <com.google.android.material.button.MaterialButton
+                android:id="@+id/btnSelectFolder"
+                style="@style/Widget.Material3Expressive.Button.OutlinedButton"
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content"
+                android:layout_marginTop="12dp"
+                android:text="@string/select_folder" />
+
+        </LinearLayout>
+
+    </com.google.android.material.card.MaterialCardView>
+
+</LinearLayout>
+