debug: add visual debug panel and comprehensive logging

- Added debug panel in terminal view that shows all terminal activity
- Added debugLog() method to TerminalManager for consistent logging
- Updated connectTerminal, handleTerminalMessage, launchCommand, createTerminal, initializeXTerm with detailed logging
- Enhanced backend logging for WebSocket messages and close codes
- Logs now show both to console and visual debug panel

This should help diagnose the terminal command execution issue without
requiring browser console access.

public/claude-ide/index.html

@@ -224,6 +224,17 @@
                         <p>Click "+ New Terminal" to get started</p>
                     </div>
                 </div>
+
+                <!-- Debug Panel -->
+                <div id="terminal-debug-panel" style="margin: 20px; padding: 15px; background: #1a1a1a; border: 1px solid #ff6b6b; border-radius: 8px; font-family: monospace; font-size: 12px; color: #e0e0e0;">
+                    <div style="display: flex; justify-content: space-between; align-items: center; margin-bottom: 10px;">
+                        <h3 style="margin: 0; color: #ff6b6b;">🐛 Terminal Debug Panel</h3>
+                        <button onclick="document.getElementById('terminal-debug-panel').style.display = 'none'" style="background: #ff6b6b; border: none; color: white; padding: 4px 12px; border-radius: 4px; cursor: pointer;">Close</button>
+                    </div>
+                    <div id="terminal-debug-content" style="max-height: 300px; overflow-y: auto;">
+                        <div style="color: #888;">Waiting for terminal activity...</div>
+                    </div>
+                </div>
             </div>
         </div>
     </div>