fix: render equations in markdown preview (#5745)

frontend/src/views/files/Editor.vue

@@ -94,6 +94,7 @@ import { useFileStore } from "@/stores/file";
 import { useLayoutStore } from "@/stores/layout";
 import { getEditorTheme } from "@/utils/theme";
 import { marked } from "marked";
+import markedKatex from "marked-katex-extension";
 import { inject, onBeforeUnmount, onMounted, ref, watchEffect } from "vue";
 import { useI18n } from "vue-i18n";
 import { onBeforeRouteUpdate, useRoute, useRouter } from "vue-router";
@@ -118,6 +119,11 @@ const previewContent = ref("");
 const isMarkdownFile =
   fileStore.req?.name.endsWith(".md") ||
   fileStore.req?.name.endsWith(".markdown");
+const katexOptions = {
+  output: "mathml" as const,
+  throwOnError: false
+};
+marked.use(markedKatex(katexOptions));
 
 const isSelectionEmpty = ref(true);