fix(app): 修复 RemoteJournalRepository API 响应解析 — 分页信封嵌套

根因: 后端列表接口返回 { success, data: { data: [...], total, ... }, message }
但前端直接 body['data'] as List，类型不匹配导致 TypeError 被静默吞掉。

修复: getJournals 和 getJournalCount 正确解析分页信封
body['data']['data'] 获取列表, body['data']['total'] 获取总数。

app/lib/data/repositories/remote_journal_repository.dart

@@ -39,7 +39,9 @@ class RemoteJournalRepository implements JournalRepository {
 
     final response = await _api.get('/diary/journals', queryParams: queryParams);
     final body = response.data as Map<String, dynamic>;
-    final items = body['data'] as List? ?? [];
+    // 后端信封格式: { success, data: { data: [...], total, page, ... }, message }
+    final envelope = body['data'] as Map<String, dynamic>? ?? {};
+    final items = envelope['data'] as List? ?? [];
     return items
         .map((json) => JournalEntry.fromJson(json as Map<String, dynamic>))
         .toList();
@@ -52,7 +54,9 @@ class RemoteJournalRepository implements JournalRepository {
       'page_size': 1,
     });
     final body = response.data as Map<String, dynamic>;
-    return (body['total'] as int?) ?? 0;
+    // 后端信封格式: { success, data: { data: [...], total, ... }, message }
+    final envelope = body['data'] as Map<String, dynamic>? ?? {};
+    return (envelope['total'] as int?) ?? 0;
   }
 
   @override