fix(mobile-app): 修复待签署合同列表重复显示问题

之前同时调用 getPendingTasks 和 getUnsignedTasks 然后合并，
导致待签署的任务显示两次。现在只使用 getUnsignedTasks。

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

frontend/mobile-app/lib/features/contract_signing/presentation/pages/pending_contracts_page.dart

@@ -21,7 +21,6 @@ class PendingContractsPage extends ConsumerStatefulWidget {
 }
 
 class _PendingContractsPageState extends ConsumerState<PendingContractsPage> {
-  List<ContractSigningTask> _pendingTasks = [];
   List<ContractSigningTask> _unsignedTasks = [];
   bool _isLoading = true;
   String? _errorMessage;
@@ -41,20 +40,16 @@ class _PendingContractsPageState extends ConsumerState<PendingContractsPage> {
     try {
       final service = ref.read(contractSigningServiceProvider);
 
-      // 并行获取待签署和未签署任务
-      final results = await Future.wait([
-        service.getPendingTasks(),
-        service.getUnsignedTasks(),
-      ]);
+      // 获取所有未签署任务（包括待签署和超时未签署）
+      final tasks = await service.getUnsignedTasks();
 
       setState(() {
-        _pendingTasks = results[0];
-        _unsignedTasks = results[1];
+        _unsignedTasks = tasks;
         _isLoading = false;
       });
 
       // 如果没有待签署任务，自动返回
-      if (_pendingTasks.isEmpty && _unsignedTasks.isEmpty) {
+      if (_unsignedTasks.isEmpty) {
         if (mounted) {
           context.pop(true);
         }
@@ -182,9 +177,7 @@ class _PendingContractsPageState extends ConsumerState<PendingContractsPage> {
       );
     }
 
-    final allTasks = [..._pendingTasks, ..._unsignedTasks];
-
-    if (allTasks.isEmpty) {
+    if (_unsignedTasks.isEmpty) {
       return const Center(
         child: Column(
           mainAxisAlignment: MainAxisAlignment.center,
@@ -209,8 +202,8 @@ class _PendingContractsPageState extends ConsumerState<PendingContractsPage> {
       color: const Color(0xFFD4AF37),
       child: ListView.builder(
         padding: const EdgeInsets.all(16),
-        itemCount: allTasks.length,
-        itemBuilder: (context, index) => _buildTaskCard(allTasks[index]),
+        itemCount: _unsignedTasks.length,
+        itemBuilder: (context, index) => _buildTaskCard(_unsignedTasks[index]),
       ),
     );
   }