feat(shiki): support `ansi` code highlight (#1878)

Co-authored-by: Divyansh Singh <40380293+brc-dd@users.noreply.github.com>

src/node/markdown/plugins/highlight.ts

@@ -88,7 +88,7 @@ export async function highlight(
 
     if (lang) {
       const langLoaded = highlighter.getLoadedLanguages().includes(lang as any)
-      if (!langLoaded) {
+      if (!langLoaded && lang !== 'ansi') {
         console.warn(
           c.yellow(
             `The language '${lang}' is not loaded, falling back to '${
@@ -127,42 +127,28 @@ export async function highlight(
       return s
     }
 
-    if (hasSingleTheme) {
+    str = removeMustache(str)
+
+    const codeToHtml = (theme: IThemeRegistration) => {
       return cleanup(
         restoreMustache(
-          highlighter.codeToHtml(removeMustache(str), {
-            lang,
-            lineOptions,
-            theme: getThemeName(theme)
-          })
+          lang === 'ansi'
+            ? highlighter.ansiToHtml(str, {
+                lineOptions,
+                theme: getThemeName(theme)
+              })
+            : highlighter.codeToHtml(str, {
+                lang,
+                lineOptions,
+                theme: getThemeName(theme)
+              })
         )
       )
     }
 
-    const dark = addClass(
-      cleanup(
-        highlighter.codeToHtml(str, {
-          lang,
-          lineOptions,
-          theme: getThemeName(theme.dark)
-        })
-      ),
-      'vp-code-dark',
-      'pre'
-    )
-
-    const light = addClass(
-      cleanup(
-        highlighter.codeToHtml(str, {
-          lang,
-          lineOptions,
-          theme: getThemeName(theme.light)
-        })
-      ),
-      'vp-code-light',
-      'pre'
-    )
-
+    if (hasSingleTheme) return codeToHtml(theme)
+    const dark = addClass(codeToHtml(theme.dark), 'vp-code-dark', 'pre')
+    const light = addClass(codeToHtml(theme.light), 'vp-code-light', 'pre')
     return dark + light
   }
 }