fix: Paragraphs in table cells skipped in import

Port HTML importer rules from enterprise fork

server/utils/turndown/underlines.ts

@@ -0,0 +1,15 @@
+import TurndownService from "turndown";
+
+/**
+ * A turndown plugin for converting u tags to underlines.
+ *
+ * @param turndownService The TurndownService instance.
+ */
+export default function underlines(turndownService: TurndownService) {
+  turndownService.addRule("underlines", {
+    filter: ["u"],
+    replacement(content) {
+      return `__${content.trim()}__`;
+    },
+  });
+}