fix: make sure page up/down works to navigate pages

Fixes #110

Author: chrrs

src/main/java/me/chrr/scribble/screen/ScribbleBookScreen.java

@@ -10,16 +10,19 @@
 import net.minecraft.client.gui.screens.Screen;
 import net.minecraft.client.gui.screens.inventory.BookViewScreen;
 import net.minecraft.client.gui.screens.inventory.PageButton;
+import net.minecraft.client.input.KeyEvent;
 import net.minecraft.client.renderer.RenderPipelines;
 import net.minecraft.network.chat.Component;
 import net.minecraft.network.chat.MutableComponent;
 import net.minecraft.network.chat.Style;
 import net.minecraft.resources.Identifier;
 import org.jspecify.annotations.NullMarked;
 import org.jspecify.annotations.Nullable;
+import org.lwjgl.glfw.GLFW;
 
 import java.util.ArrayList;
 import java.util.List;
+import java.util.Objects;
 
 @NullMarked
 public abstract class ScribbleBookScreen<T> extends Screen {
@@ -169,6 +172,19 @@ public void goPageBackward(boolean toStart) {
             showPage(this.currentPage - 1, false);
         }
     }
+
+    @Override
+    public boolean keyPressed(KeyEvent event) {
+        if (event.key() == GLFW.GLFW_KEY_PAGE_UP) {
+            Objects.requireNonNull(this.backButton).onPress(event);
+            return true;
+        } else if (event.key() == GLFW.GLFW_KEY_PAGE_DOWN) {
+            Objects.requireNonNull(this.forwardButton).onPress(event);
+            return true;
+        }
+
+        return super.keyPressed(event);
+    }
     //endregion
 
     //region Rendering and dimensions