feat: surface admin load errors

lib/screens/schedules_screen.dart

@@ -1,6 +1,9 @@
 import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
+import '../app/error_message.dart';
+import '../app/load_state.dart';
 import '../providers/providers.dart';
+import '../widgets/load_error_view.dart';
 
 /// Экран управления расписаниями.
 /// Показывает все задачи (one-shot и cron), позволяет создавать и удалять.
@@ -12,8 +15,6 @@ class SchedulesScreen extends ConsumerStatefulWidget {
 }
 
 class _SchedulesScreenState extends ConsumerState<SchedulesScreen> {
-  bool _loading = true;
-
   @override
   void initState() {
     super.initState();
@@ -22,45 +23,16 @@ class _SchedulesScreenState extends ConsumerState<SchedulesScreen> {
 
   Future<void> _load() async {
     await ref.read(tasksProvider.notifier).load();
-    if (mounted) setState(() => _loading = false);
   }
 
   @override
   Widget build(BuildContext context) {
-    final tasks = ref.watch(tasksProvider);
+    final tasksState = ref.watch(tasksProvider);
+    final tasks = tasksState.data;
 
     return Scaffold(
       appBar: AppBar(title: const Text('РАСПИСАНИЯ')),
-      body: _loading
-          ? const Center(
-              child: CircularProgressIndicator(color: Colors.deepOrange),
-            )
-          : tasks.isEmpty
-          ? const Center(
-              child: Column(
-                mainAxisAlignment: MainAxisAlignment.center,
-                children: [
-                  Icon(Icons.schedule, size: 64, color: Colors.white24),
-                  SizedBox(height: 16),
-                  Text(
-                    'Нет активных расписаний',
-                    style: TextStyle(color: Colors.white54, fontSize: 16),
-                  ),
-                ],
-              ),
-            )
-          : RefreshIndicator(
-              color: Colors.deepOrange,
-              onRefresh: () => ref.read(tasksProvider.notifier).load(),
-              child: ListView.builder(
-                padding: const EdgeInsets.all(12),
-                itemCount: tasks.length,
-                itemBuilder: (context, index) {
-                  final task = tasks[index];
-                  return _TaskCard(task: task);
-                },
-              ),
-            ),
+      body: _buildContent(tasksState, tasks),
       floatingActionButton: FloatingActionButton(
         backgroundColor: Colors.deepOrange,
         onPressed: () => _showAddDialog(context),
@@ -81,6 +53,74 @@ class _SchedulesScreenState extends ConsumerState<SchedulesScreen> {
       builder: (ctx) => const _AddScheduleSheet(),
     );
   }
+
+  Widget _buildContent(
+    LoadState<List<dynamic>> tasksState,
+    List<dynamic> tasks,
+  ) {
+    if ((tasksState.isIdle || tasksState.isLoading) && tasks.isEmpty) {
+      return const Center(
+        child: CircularProgressIndicator(color: Colors.deepOrange),
+      );
+    }
+
+    if (tasksState.hasError && tasks.isEmpty) {
+      return LoadErrorView(
+        title: 'Не удалось загрузить расписания',
+        message: tasksState.errorMessage,
+        icon: Icons.schedule,
+        onRetry: _load,
+      );
+    }
+
+    if (tasks.isEmpty) {
+      return const Center(
+        child: Column(
+          mainAxisAlignment: MainAxisAlignment.center,
+          children: [
+            Icon(Icons.schedule, size: 64, color: Colors.white24),
+            SizedBox(height: 16),
+            Text(
+              'Нет активных расписаний',
+              style: TextStyle(color: Colors.white54, fontSize: 16),
+            ),
+          ],
+        ),
+      );
+    }
+
+    final hasStatusHeader = tasksState.isLoading || tasksState.hasError;
+    final statusHeaderCount = hasStatusHeader ? 1 : 0;
+
+    return RefreshIndicator(
+      color: Colors.deepOrange,
+      onRefresh: _load,
+      child: ListView.builder(
+        physics: const AlwaysScrollableScrollPhysics(),
+        padding: const EdgeInsets.all(12),
+        itemCount: tasks.length + statusHeaderCount,
+        itemBuilder: (context, index) {
+          if (hasStatusHeader && index == 0) {
+            if (tasksState.isLoading) {
+              return const Padding(
+                padding: EdgeInsets.only(bottom: 12),
+                child: LinearProgressIndicator(color: Colors.deepOrange),
+              );
+            }
+
+            return LoadErrorBanner(
+              title: 'Не удалось обновить расписания',
+              message: tasksState.errorMessage,
+              onRetry: _load,
+            );
+          }
+
+          final taskIndex = index - statusHeaderCount;
+          return _TaskCard(task: tasks[taskIndex]);
+        },
+      ),
+    );
+  }
 }
 
 /// Карточка одной задачи расписания
@@ -151,9 +191,20 @@ class _TaskCard extends ConsumerWidget {
             child: const Text('Нет'),
           ),
           TextButton(
-            onPressed: () {
+            onPressed: () async {
               Navigator.of(ctx).pop();
-              ref.read(tasksProvider.notifier).cancel(jobId);
+              try {
+                await ref.read(tasksProvider.notifier).cancel(jobId);
+              } catch (e) {
+                if (!context.mounted) return;
+                ScaffoldMessenger.of(context).showSnackBar(
+                  SnackBar(
+                    content: Text(
+                      'Ошибка отмены задачи: ${describeLoadError(e)}',
+                    ),
+                  ),
+                );
+              }
             },
             child: const Text('Да', style: TextStyle(color: Colors.redAccent)),
           ),
@@ -363,9 +414,9 @@ class _AddScheduleSheetState extends ConsumerState<_AddScheduleSheet> {
       if (mounted) Navigator.of(context).pop();
     } catch (e) {
       if (mounted) {
-        ScaffoldMessenger.of(
-          context,
-        ).showSnackBar(SnackBar(content: Text('Ошибка: $e')));
+        ScaffoldMessenger.of(context).showSnackBar(
+          SnackBar(content: Text('Ошибка: ${describeLoadError(e)}')),
+        );
       }
     }
   }