refactor(settings): remove filing info config and readers

Drop the 备案信息 group (icp_filing, police_filing, footer_text) from the
global.common PHP/Vue schemas, the FacadeBulk readers and the
get_global_settings() payload. No frontend consumer existed.

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

src/Settings/DisplayPageGroups.php

@@ -154,8 +154,6 @@ trait DisplayPageGroups {
             'logo_text'                   => self::logo_text(),
             'logo_width'                  => self::logo_width(),
             'site_favicon'                => self::favicon_url(),
-            'icp_filing'                  => self::icp_filing(),
-            'footer_text'                 => self::footer_text(),
             'theme_mode'                  => self::theme_mode(),
             'theme_mode_button'           => self::get_theme_mode_button_positions(),
             'primary_color'               => self::primary_color(),