Fix: Markdow Copy now works over non-secure HTTP

frontend/src/App.tsx

@@ -442,8 +442,27 @@ export default function App() {
   const handleExportMd = useCallback(async () => {
     const md = generateMarkdownTable(nodes)
     if (!md) { toast.error('No nodes to export'); return }
-    await navigator.clipboard.writeText(md)
-    toast.success('Markdown table copied to clipboard')
+    if (navigator.clipboard && window.isSecureContext) {
+      await navigator.clipboard.writeText(md)
+      toast.success('Markdown table copied to clipboard')
+    } else {
+      // Only allowed access to navigator.clipboard over HTTPS not HTTP
+      // Use the temporary 'hidden text area for alternative copy method
+      const textArea = document.createElement("textarea");
+      textArea.value = md;
+      textArea.style.position = "absolute";
+      textArea.style.left = "-999999px";
+      document.body.prepend(textArea);
+      textArea.select();
+      try {
+        document.execCommand('copy');
+        toast.success("Markdown table copied to clipboard")
+      } catch (err) {
+        toast.error(`Markdown copy failed: ${err instanceof Error ? err.message : String(err)}`)
+      } finally {
+        textArea.remove();
+      }
+    }
   }, [nodes])
 
   const handleExportYaml = useCallback(() => {