Lots of improvements

frontend/src/lib/clipboard.ts

@@ -0,0 +1,16 @@
+/** Copy text to clipboard with execCommand fallback for older browsers. */
+export function copyToClipboard(text: string, onSuccess: () => void): void {
+  if (navigator.clipboard?.writeText) {
+    navigator.clipboard.writeText(text).then(onSuccess);
+  } else {
+    const ta = document.createElement('textarea');
+    ta.value = text;
+    ta.style.position = 'fixed';
+    ta.style.opacity = '0';
+    document.body.appendChild(ta);
+    ta.select();
+    document.execCommand('copy');
+    document.body.removeChild(ta);
+    onSuccess();
+  }
+}