fix(layout): align color scheme, content width and fonts with reference theme

- Color scheme: zibll field order/labels, theme_skin_custom overrides palette,
  hex palette swatches, dark_theme_skin_custom, light/dark background images,
  close_backdrop via body.fps-accelerat, theme_main_radius drives --main-radius
- Emit --theme-color / --focus-shadow-color / --focus-color-opacity* vars
- Drop border_radius, primary_color readers and legacy value maps
- Content max width: free 1200-2200 number field; fix font family/custom stack

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/Settings/DisplayPageGroups.php

@@ -156,13 +156,15 @@ trait DisplayPageGroups {
             'site_favicon'                => self::favicon_url(),
             'theme_mode'                  => self::theme_mode(),
             'theme_mode_button'           => self::get_theme_mode_button_positions(),
-            'primary_color'               => self::primary_color(),
-            'border_radius'               => self::border_radius(),
-            'theme_main_radius'           => self::card_radius(),
+            'theme_color'                 => self::theme_color(),
+            'dark_theme_color'            => self::dark_theme_color(),
+            'theme_main_radius'           => self::main_radius(),
+            'close_backdrop'              => self::close_backdrop(),
             'qj_loading'                  => self::is_qj_loading_enabled(),
             'qj_dh_xs'                    => self::get_qj_loading_style(),
             'container_max_width'         => self::container_max_width(),
             'font_family'                 => self::font_family(),
+            'font_family_custom'          => self::font_family_custom(),
 			'search_type'                 => !isset($s['search_type']) || !empty($s['search_type']),
 			'search_type_in'              => sanitize_key((string) ($s['search_type_in'] ?? 'post')),
 			'search_placeholder'          => self::search_placeholder(),