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.

services/terminal-service.js

@@ -100,6 +100,7 @@ class TerminalService {
         const terminal = this.terminals.get(terminalId);
 
         if (!terminal) {
+            console.error(`[TerminalService] TERMINAL NOT FOUND: ${terminalId}`);
             ws.close(1008, 'Terminal not found');
             return;
         }
@@ -108,14 +109,18 @@ class TerminalService {
         terminal.lastActivity = new Date().toISOString();
 
         console.log(`[TerminalService] WebSocket connected for terminal ${terminalId}`);
+        console.log(`[TerminalService] Terminal info - workingDir: ${terminal.workingDir}, mode: ${terminal.mode}`);
 
         // Handle incoming messages from client (user input)
         ws.on('message', (data) => {
+            console.log(`[TerminalService] Message received from ${terminalId}: ${data.toString()}`);
             try {
                 const message = JSON.parse(data);
+                console.log(`[TerminalService] Parsed message type: ${message.type}`);
 
                 if (message.type === 'input') {
                     // User typed something - send to PTY
+                    console.log(`[TerminalService] Writing to PTY: "${message.data.replace(/\n/g, '\\n')}"`);
                     terminal.pty.write(message.data);
                     terminal.lastActivity = new Date().toISOString();
 
@@ -125,6 +130,7 @@ class TerminalService {
                     }
                 } else if (message.type === 'resize') {
                     // Handle terminal resize
+                    console.log(`[TerminalService] Resize to ${message.cols}x${message.rows}`);
                     terminal.pty.resize(message.cols, message.rows);
                 }
             } catch (error) {
@@ -160,8 +166,8 @@ class TerminalService {
         });
 
         // Handle WebSocket close
-        ws.on('close', () => {
-            console.log(`[TerminalService] WebSocket closed for terminal ${terminalId}`);
+        ws.on('close', (code, reason) => {
+            console.log(`[TerminalService] WebSocket closed for terminal ${terminalId} - code: ${code}, reason: ${reason || 'none'}`);
 
             // Don't kill PTY immediately - allow reconnection
             // PTY will be killed after timeout or explicit close
@@ -173,12 +179,15 @@ class TerminalService {
         });
 
         // Send initial welcome message
-        ws.send(JSON.stringify({
+        const readyMessage = JSON.stringify({
             type: 'ready',
             terminalId,
             workingDir: terminal.workingDir,
             mode: terminal.mode
-        }));
+        });
+        console.log(`[TerminalService] Sending ready message to ${terminalId}: ${readyMessage}`);
+        ws.send(readyMessage);
+        console.log(`[TerminalService] Ready message sent successfully`);
     }
 
     /**