feat: add ICP 备案 & provisional 公安备案 info to footer

公安备案 link is hidden at first, to allow quick merging of this PR once
the ICP 备案 number is officially approved. A follow-up PR will take
care of finalizing and exposing the other bits.

src/theme/Footer/Copyright/index.tsx

@@ -1,10 +1,50 @@
 import React from 'react'
 import Copyright from '@theme-original/Footer/Copyright'
 
+import styles from './styles.module.css'
+
+function ICPBeianLink(
+  {
+    province,
+    recordNumber,
+    subRecordNumber,
+  }: {
+    province: string,
+    recordNumber: number,
+    subRecordNumber: number,
+  },
+): JSX.Element {
+  return (
+    <a href="https://beian.miit.gov.cn" target="_blank">{province}ICP备{recordNumber}号-{subRecordNumber}</a>
+  )
+}
+
+function MPSBeianLink(
+  {
+    province,
+    recordNumber,
+  }: {
+    province: string,
+    recordNumber: number,
+  },
+): JSX.Element {
+  const queryLinkURL = `http://www.beian.gov.cn/portal/registerSystemInfo?recordcode=${recordNumber}`
+  return (
+    <>
+      <img src="/img/mps-beian-logo.webp" height="28" className={styles.mpsLogo} />
+      <a href={queryLinkURL} target="_blank">{province}公网安备{recordNumber}号</a>
+    </>
+  )
+}
+
 export default function CopyrightWrapper(props: any): JSX.Element {
   return (
     <>
       <Copyright {...props} />
+      <ul className={styles.footer__beian}>
+        <li><ICPBeianLink province="苏" recordNumber={17027553} subRecordNumber={2} /></li>
+        {/* <li><MPSBeianLink province="沪" recordNumber={11223344001122} /></li> */}
+      </ul>
     </>
   )
 }

src/theme/Footer/Copyright/styles.module.css

@@ -0,0 +1,10 @@
+/* 备案信息 */
+.footer__beian li {
+  list-style: none;
+  display: inline;
+}
+
+.mpsLogo {
+  margin: 0 0.5rem;
+  vertical-align: text-bottom;
+}