Fix copy button in iframe and reduce line-height spacing

- Always try clipboard API first, fall through to execCommand fallback
  on failure (fixes iframe/SharePoint where clipboard API throws)
- Reduce line-height from 1.6 to 1.3 in components.css to fix large
  gaps between lines in bot responses

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/src/components/ChatInterface.tsx

@@ -38,22 +38,26 @@ const ChatInterface: React.FC = () => {
     }
   }, [messageText]);
 
+  const copyToClipboardFallback = (text: string) => {
+    const textArea = document.createElement('textarea');
+    textArea.value = text;
+    textArea.style.position = 'fixed';
+    textArea.style.left = '-9999px';
+    textArea.style.top = '-9999px';
+    document.body.appendChild(textArea);
+    textArea.focus();
+    textArea.select();
+    document.execCommand('copy');
+    document.body.removeChild(textArea);
+  };
+
   const handleCopyMessage = async (messageId: string, content: string) => {
     try {
-      if (navigator.clipboard && window.isSecureContext) {
+      try {
         await navigator.clipboard.writeText(content);
-      } else {
-        // Fallback for iframe/non-secure contexts (SharePoint)
-        const textArea = document.createElement('textarea');
-        textArea.value = content;
-        textArea.style.position = 'fixed';
-        textArea.style.left = '-9999px';
-        textArea.style.top = '-9999px';
-        document.body.appendChild(textArea);
-        textArea.focus();
-        textArea.select();
-        document.execCommand('copy');
-        document.body.removeChild(textArea);
+      } catch {
+        // Clipboard API failed (iframe/permissions) — use fallback
+        copyToClipboardFallback(content);
       }
       setCopiedMessageId(messageId);
       setTimeout(() => setCopiedMessageId(null), 2000);

frontend/src/styles/components.css

@@ -156,7 +156,7 @@
   border-radius: var(--radius-md);
   box-shadow: var(--shadow-sm);
   font-size: var(--font-size-base);
-  line-height: 1.6;
+  line-height: 1.3;
   color: var(--text-primary);
 }