fix(runtime): onGenerateRoute pathElements 越界 RangeError

- buy-service/renew-minioffice 加长度检查 (pathElements.length >= 4/3)
- 根因: Flutter web 深链接渐进式路径解析, onGenerateRoute 被调用多次,
  pathElements 递增 ([,buy-service] -> [,buy-service,1] -> 完整),
  前几次路径短但 pathElements[1]已匹配 -> int.parse([2])/[3] 越界
- 直接访问/刷新 /buy-service/x/y, /renew-minioffice/x 时崩溃
- 恢复 buy_service 实验代码 (data 校验 + mounted 保留)

lib/main.dart

@@ -36,7 +36,7 @@ void main() {
   FlutterError.onError = (details) {
     FlutterError.presentError(details);
     print('CK_ERROR: ${details.exceptionAsString()}');
-    print('CK_CTX: ${details.context.toString()}');
+    print('CK_CTX: ${details.context}');
     print('CK_STACK: ${details.stack}');
   };
   // Enable configureApp will cause route problem.
@@ -171,12 +171,12 @@ class MyApp extends StatelessWidget {
                 ),
           );
         }
-        if (pathElements[1] == 'renew-minioffice') {
+        if (pathElements[1] == 'renew-minioffice' && pathElements.length >= 3) {
           return MaterialPageRoute(builder: (BuildContext context) =>
             RenewMiniOffice(int.parse(pathElements[2]))
           );
         }
-        if (pathElements[1] == 'buy-service') {
+        if (pathElements[1] == 'buy-service' && pathElements.length >= 4) {
           return MaterialPageRoute(builder: (BuildContext context) =>
             BuyService(int.parse(pathElements[2]), pathElements[3])
           );