feat(import/markdown): basic support for admonitions

src/services/import/markdown.ts

@@ -3,6 +3,7 @@
 import { parse, Renderer, type Tokens } from "marked";
 import { minify as minifyHtml } from "html-minifier";
 
+// Keep renderer code up to date with https://github.com/markedjs/marked/blob/master/src/Renderer.ts.
 const renderer = new Renderer({ async: false });
 renderer.code = ({ text, lang, escaped }: Tokens.Code) => {
     if (!text) {
@@ -12,10 +13,29 @@ renderer.code = ({ text, lang, escaped }: Tokens.Code) => {
     const ckEditorLanguage = getNormalizedMimeFromMarkdownLanguage(lang);
     return `<pre><code class="language-${ckEditorLanguage}">${text}</code></pre>`;
 };
+renderer.blockquote = ({ tokens }: Tokens.Blockquote) => {
+    const body = renderer.parser.parse(tokens);
+
+    const admonitionMatch = /^<p>\[\!([A-Z]+)\]/.exec(body);
+    if (Array.isArray(admonitionMatch) && admonitionMatch.length === 2) {
+        const type = admonitionMatch[1].toLowerCase();
+
+        if (ADMONITION_TYPE_MAPPINGS[type]) {
+            const bodyWithoutHeader = body
+                .replace(/^<p>\[\!([A-Z]+)\]/, "<p>")
+                .replace(/^<p><\/p>/, ""); // Having a heading will generate an empty paragraph that we need to remove.
+
+            return `<aside class="admonition ${type}">\n${bodyWithoutHeader}</aside>\n`;
+        }
+    }
+
+    return `<blockquote>\n${body}</blockquote>\n`;
+};
 
 import htmlSanitizer from "../html_sanitizer.js";
 import importUtils from "./utils.js";
 import { getMimeTypeFromHighlightJs, MIME_TYPE_AUTO, normalizeMimeTypeForCKEditor } from "./mime_type_definitions.js";
+import { ADMONITION_TYPE_MAPPINGS } from "../export/markdown.js";
 
 function renderToHtml(content: string, title: string) {
     let html = parse(content, {