Ensure dialog:selectFolder IPC handler always sends reply

Add try-catch wrapper and isDestroyed() check to prevent "reply was
never sent" errors when the window closes during dialog operations.

Fixes MAESTRO-58

src/main/ipc/handlers/system.ts

@@ -61,9 +61,13 @@ export function registerSystemHandlers(deps: SystemHandlerDependencies): void {
 	// ============ Dialog Handlers ============
 
 	// Folder selection dialog
+	// Wrapped in try-catch to ensure a reply is always sent, even if the window
+	// is closed while the dialog is open or other unexpected errors occur.
+	// Fixes MAESTRO-58: "reply was never sent"
 	ipcMain.handle('dialog:selectFolder', async () => {
+		try {
 			const mainWindow = getMainWindow();
-		if (!mainWindow) return null;
+			if (!mainWindow || mainWindow.isDestroyed()) return null;
 
 			const result = await dialog.showOpenDialog(mainWindow, {
 				properties: ['openDirectory', 'createDirectory'],
@@ -75,6 +79,11 @@ export function registerSystemHandlers(deps: SystemHandlerDependencies): void {
 			}
 
 			return result.filePaths[0];
+		} catch (error) {
+			// Log the error but return null to ensure IPC reply is sent
+			logger.error('dialog:selectFolder failed', 'Dialog', { error });
+			return null;
+		}
 	});
 
 	// File save dialog