feat: enable IMAP trace logging in debug builds

Sets isLogEnabled=kDebugMode on ImapClient so raw IMAP traffic appears
in the debug console without touching release builds.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

lib/data/imap/imap_client_factory.dart

@@ -1,4 +1,5 @@
 import 'package:enough_mail/enough_mail.dart';
+import 'package:flutter/foundation.dart';
 
 import '../../core/models/account.dart';
 
@@ -21,8 +22,10 @@ Future<ImapClient> connectImap(
       'Unencrypted IMAP connections are not allowed. Enable SSL/TLS.',
     );
   }
-  final client =
-      ImapClient(defaultResponseTimeout: const Duration(seconds: 20));
+  final client = ImapClient(
+    defaultResponseTimeout: const Duration(seconds: 20),
+    isLogEnabled: kDebugMode,
+  );
   await client.connectToServer(account.imapHost, account.imapPort);
   await client.login(username, password);
   return client;