fix(core): make the atom format spec-compliant (#20723)

* fix: remove the src attribute of atom:content

The src attribute is to replace the inner content, not to mark its source.

RFC4287:

> 4.1.3.2.  The "src" Attribute
>
>  atom:content MAY have a "src" attribute, whose value MUST be an IRI
>  reference [RFC3987].  If the "src" attribute is present, atom:content
>  MUST be empty.  Atom Processors MAY use the IRI to retrieve the
>  content and MAY choose to ignore remote content or to present it in a
>  different manner than local content.
>
>  If the "src" attribute is present, the "type" attribute SHOULD be
>  provided and MUST be a MIME media type [MIMEREG], rather than "text",
>  "html", or "xhtml".  The value is advisory; that is to say, when the
>  corresponding URI (mapped from an IRI, if necessary) is dereferenced,
>  if the server providing that content also provides a media type, the
>  server-provided media type is authoritative.

* fix: move <language> to xml:lang

* fix: remove <webMaster> in atom

* fix: use ISO format to display date in atom & always have <updated>

* fix: use ISO date for feed <updated> in atom

* fix: add <link rel=self> for atom

lib/views/atom.tsx

@@ -3,15 +3,14 @@ import type { FC } from 'hono/jsx';
 import type { Data } from '@/types';
 
 const RSS: FC<{ data: Data }> = ({ data }) => (
-    <feed xmlns="http://www.w3.org/2005/Atom" xmlns:rsshub="http://rsshub.app/xml/schemas">
+    <feed xmlns="http://www.w3.org/2005/Atom" xmlns:rsshub="http://rsshub.app/xml/schemas" xml:lang={data.language || 'en'}>
         <title>{data.title || 'RSSHub'}</title>
-        <link href={data.link || 'https://docs.rsshub.app'} />
+        <link rel="alternate" href={data.link || 'https://docs.rsshub.app'} />
+        <link rel="self" href={data.atomlink} type="application/atom+xml" />
         <id>{data.id || data.link}</id>
         <subtitle>{data.description || data.title} - Powered by RSSHub</subtitle>
         <generator>RSSHub</generator>
-        <webMaster>contact@rsshub.app (RSSHub)</webMaster>
-        <language>{data.language || 'en'}</language>
-        <updated>{data.lastBuildDate}</updated>
+        <updated>{new Date(data.lastBuildDate || new Date()).toISOString()}</updated>
         <author>
             <name>{data.author || 'RSSHub'}</name>
         </author>
@@ -21,13 +20,11 @@ const RSS: FC<{ data: Data }> = ({ data }) => (
         {data.item?.map((item) => (
             <entry>
                 <title>{item.title}</title>
-                <content type="html" src={item.link}>
-                    {item.description}
-                </content>
+                <content type="html">{item.description}</content>
                 <link href={item.link} />
                 <id>{item.guid || item.link || item.title}</id>
-                {item.pubDate && <published>{item.pubDate}</published>}
-                {item.updated && <updated>{item.updated || item.pubDate}</updated>}
+                {item.pubDate && <published>{new Date(item.pubDate).toISOString()}</published>}
+                <updated>{new Date(item.updated || item.pubDate || new Date()).toISOString()}</updated>
                 {item.author && (
                     <author>
                         <name>{item.author}</name>