feat: Add graceful QB connection shutdown and enhanced logout UI

- Add graceful shutdown handler to properly close QB sessions on server stop
- Enhance /quickbooks/logout endpoint with detailed logging and error handling
- Style logout button as 'danger' action with clear QB connection closing label
- Improve logout feedback with timestamps and error messaging
- Update user to aewing in .env for QB authentication

Mode3/frontend/index.html

@@ -65,6 +65,12 @@
         button:hover {
             background: #5568d3;
         }
+        button.danger {
+            background: #dc3545;
+        }
+        button.danger:hover {
+            background: #c82333;
+        }
         .form-group {
             margin: 15px 0;
         }
@@ -136,7 +142,7 @@
                 <p><strong>Company File:</strong> <span id="companyFile"></span></p>
                 <p><strong>User:</strong> <span id="sessionUser"></span></p>
                 <p><strong>Expires:</strong> <span id="sessionExpires"></span></p>
-                <button onclick="logout()">Logout</button>
+                <button class="danger" onclick="logout()">🔌 Close QB Connection / Logout</button>
             </div>
         </div>
 
@@ -359,9 +365,15 @@
                 if (data.success) {
                     updateSessionInfo();
                     document.getElementById('authMessage').className = 'message success';
-                    document.getElementById('authMessage').textContent = '✓ ' + data.message;
+                    const timestamp = data.closedAt ? ` (${new Date(data.closedAt).toLocaleTimeString()})` : '';
+                    document.getElementById('authMessage').textContent = '✓ ' + data.message + timestamp;
+                } else {
+                    document.getElementById('authMessage').className = 'message error';
+                    document.getElementById('authMessage').textContent = '✗ ' + (data.error || 'Logout failed');
                 }
             } catch (error) {
+                document.getElementById('authMessage').className = 'message error';
+                document.getElementById('authMessage').textContent = '✗ Logout failed: ' + error.message;
                 console.error('Logout failed:', error);
             }
         }