Migrate "readerWidth" reader setting

src/modules/metadata/Metadata.constants.ts

@@ -289,6 +289,11 @@ export const METADATA_MIGRATIONS: IMetadataMigration[] = [
                 newValue: `${ReaderPageScaleMode.SCREEN}`,
             },
             // END: fitPageToWindow
+            {
+                key: 'readerWidth',
+                oldValue: /[0-9]+/g,
+                newValue: (oldValue) => JSON.stringify({ value: Number(oldValue), enabled: true }),
+            },
         ],
     },
 ];