refactor: Replace async clipboard method with more reliable execCommand approach

src/streamlit_app.py

@@ -531,18 +531,20 @@ if st.session_state.error_log:
         
         js_code = f"""
             <script>
-                async function copyToClipboard() {{
-                    try {{
-                        const text = `{escaped_error_text}`;
-                        await navigator.clipboard.writeText(text);
-                        return true;
-                    }} catch (err) {{
-                        console.error('Failed to copy text: ', err);
-                        return false;
-                    }}
+                var textArea = document.createElement("textarea");
+                textArea.value = `{escaped_error_text}`;
+                document.body.appendChild(textArea);
+                textArea.select();
+                try {{
+                    document.execCommand('copy');
+                    textArea.remove();
+                    window.parent.document.querySelector('iframe').contentWindow.postMessage({{copied: true}}, '*');
+                }} catch (err) {{
+                    console.error('Failed to copy text: ', err);
+                    textArea.remove();
                 }}
-                copyToClipboard();
             </script>
+            <div id="result"></div>
         """
         st.components.v1.html(js_code, height=0)
         st.success("✅ Error log copied to clipboard!")