fix: translate only static strings in unread drawer menu

Translating menuEl.innerHTML re-serialized untrusted topic titles into
HTML and reinjected them via innerHTML. Translate only the two static
placeholder strings ([[unread:no-unread-topics]], [[unread:title]])
via a small textContent-based helper instead.

public/client.js

@@ -159,6 +159,16 @@
 			});
 	}
 
+	function translateText(el) {
+		if (window.require) {
+			window.require(['translator'], function (translator) {
+				translator.translate(el.textContent, (translated) => {
+					el.textContent = translated;
+				});
+			});
+		}
+	}
+
 	function renderUnreadMenu(menuEl, topics) {
 		if (!menuEl) {
 			return;
@@ -179,6 +189,7 @@
 			empty.className = 'dropdown-item disabled';
 			empty.textContent = '[[unread:no-unread-topics]]';
 			addItem(empty);
+			translateText(empty);
 		}
 
 		list.forEach((topic) => {
@@ -204,14 +215,7 @@
 		seeAll.href = `${relativePath}/unread`;
 		seeAll.textContent = '[[unread:title]]';
 		addItem(seeAll);
-
-		if (window.require) {
-			window.require(['translator'], function (translator) {
-				translator.translate(menuEl.innerHTML, (translated) => {
-					menuEl.innerHTML = translated;
-				});
-			});
-		}
+		translateText(seeAll);
 	}
 
 	function getWestgateTopbar() {