refactor(reader): remove test font, move settings panel to right sidebar

- Remove Playwrite NZ Guides test font and all references (FONT_MAP,
  FONT_FILES, reader-fonts.css, dropdown option, font files)
- Move settings panel from left sidebar to right sidebar (left sidebar
  now only contains TOC)
- Move Restore Defaults button from top bar icon to a styled button
  inside the settings panel, side by side with Done button

web/static/reader-fonts.css

@@ -227,11 +227,3 @@
   font-weight: 700;
   font-style: italic;
 }
-
-@font-face {
-  font-family: "Playwrite NZ Guides";
-  src: url("/static/fonts/Playwrite_NZ_Guides/PlaywriteNZGuides-Regular.woff2")
-    format("woff2");
-  font-weight: 400;
-  font-style: normal;
-}