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>

assets/admin/src/constants/sections/global.js

@@ -12,7 +12,7 @@ export const globalSection = {
       label: '常用功能',
       route: '/global/common',
       title: '常用功能',
-      desc: '评论、性能、头像源与备案等全局基础配置。',
+      desc: '评论、性能、头像源等全局基础配置。',
       canonicalDomain: 'global',
       section: 'common',
     }),