Fix auto-retry cap never being reached in KretenLoginWidget

_autoRetryCount was reset to 0 in onPageStarted, which fires after
every loadRequest call including the one inside _retryLoad. This meant
the retry cap (_maxAutoRetries = 1) was never reached, causing an
infinite retry loop on persistent errors.

Move the _autoRetryCount reset to onPageFinished so it only clears
when the page actually loads successfully (or via the user-initiated
_retry which already resets it explicitly).

https://claude.ai/code/session_016dhktF2DaoTQeifUaZrxbP

refilc_mobile_ui/lib/screens/login/kreten_login.dart

@@ -112,7 +112,6 @@ class _KretenLoginWidgetState extends State<KretenLoginWidget>
             }
           });
 
-          _autoRetryCount = 0;
           _startTimeoutTimer();
         },
         onProgress: (progress) {
@@ -127,6 +126,7 @@ class _KretenLoginWidgetState extends State<KretenLoginWidget>
 
           if (!mounted) return;
 
+          _autoRetryCount = 0;
           setState(() {
             currentUrl = url;
             _initialPageLoaded = true;