refactor(config): 服务地址改为 dev/prod 配置文件与单个环境开关

启动时按环回、局域网、公网顺序探测地址，换网络后会静默切到别处，排查
困难。改为代码内一个布尔开关选择环境，地址分别放在 dev_config.dart 与
prod_config.dart，不再探测；调试条改地址后直接重载，不再重新探测。
release 构建若仍是开发开关会启动即报错，避免线上包连开发机。

test/home/catalog_diagnostics_test.dart

@@ -6,7 +6,6 @@ import 'package:flutter/material.dart';
 import 'package:flutter_test/flutter_test.dart';
 
 import 'package:fruitshorts/core/config/app_config.dart';
-import 'package:fruitshorts/core/data/services/catalog_retry.dart';
 import 'package:fruitshorts/core/theme/app_colors.dart';
 import 'package:fruitshorts/core/widgets/catalog_endpoint_editor.dart';
 import 'package:fruitshorts/l10n/app_localizations.dart';
@@ -55,20 +54,7 @@ void main() {
     );
   });
 
-  test('should_probe_before_reloading_catalog', () async {
-    final steps = <String>[];
-
-    await retryCatalogLoad(
-      probe: () async => steps.add('probe'),
-      reload: () async => steps.add('load'),
-    );
-
-    expect(steps, ['probe', 'load']);
-  });
-
-  testWidgets('should_save_probe_and_reload_after_valid_endpoint', (
-    tester,
-  ) async {
+  testWidgets('should_save_and_reload_after_valid_endpoint', (tester) async {
     AppConfig.applyRuntimeBaseUrl('http://127.0.0.1:8081');
     final steps = <String>[];
     await _pumpEndpointEditor(
@@ -77,7 +63,6 @@ void main() {
         steps.add('save:$value');
         return true;
       },
-      probe: () async => steps.add('probe'),
       reload: () async => steps.add('load'),
     );
 
@@ -101,12 +86,11 @@ void main() {
     await tester.tap(find.byKey(const Key('catalog-debug-endpoint-save')));
     await tester.pumpAndSettle();
 
-    expect(steps, ['save:http://10.0.0.8:8081', 'probe', 'load']);
+    expect(steps, ['save:http://10.0.0.8:8081', 'load']);
   });
 
   testWidgets('should_reject_invalid_endpoint_without_saving', (tester) async {
     var saves = 0;
-    var probes = 0;
     var loads = 0;
     await _pumpEndpointEditor(
       tester,
@@ -114,7 +98,6 @@ void main() {
         saves++;
         return true;
       },
-      probe: () async => probes++,
       reload: () async => loads++,
     );
 
@@ -134,7 +117,6 @@ void main() {
       findsOneWidget,
     );
     expect(saves, 0);
-    expect(probes, 0);
     expect(loads, 0);
   });
 }
@@ -142,7 +124,6 @@ void main() {
 Future<void> _pumpEndpointEditor(
   WidgetTester tester, {
   required Future<bool> Function(String value) save,
-  required Future<void> Function() probe,
   required Future<void> Function() reload,
 }) async {
   await tester.pumpWidget(
@@ -152,12 +133,7 @@ Future<void> _pumpEndpointEditor(
           body: TextButton(
             key: const Key('open-endpoint-editor'),
             onPressed: () => unawaited(
-              showCatalogEndpointEditor(
-                context,
-                save: save,
-                probe: probe,
-                reload: reload,
-              ),
+              showCatalogEndpointEditor(context, save: save, reload: reload),
             ),
             child: const Text('open'),
           ),