feat(frontend): open sidebar media on click, unbreak long-press menus

frontend/src/lib/viewport.ts

@@ -0,0 +1,7 @@
+import { browser } from "$app/environment";
+
+const MOBILE_QUERY = "(max-width: 600px)";
+
+export function isMobile(): boolean {
+  return browser && window.matchMedia(MOBILE_QUERY).matches;
+}