feat(app): 设置页 UI + Mood/成就/贴纸 BLoC 接入 API + B7 测试扩展

前端改动:
- 新建设置页面 (主题切换/关于/隐私政策/用户协议/儿童隐私保护)
- SettingsBloc 注册到 MultiRepositoryProvider 全局可访问
- MoodBloc 修复编译错误 + 接入 /diary/stats/mood API
- MoodPage 添加错误状态展示和重试按钮
- AchievementBloc + 页面改造接入 /diary/achievements API
- StickerBloc + 页面改造接入 /diary/sticker-packs API
- TemplateBloc + 页面改造接入 /diary/templates API
- ProfilePage 设置入口改为跳转 /settings
- 添加 /settings 路由

后端改动:
- 扩展 mood_stats_service 测试 (连续天数算法/心情计数/边界场景)
- 新增 class_service 测试 (班级码生成/唯一性/错误映射)
- 新增 achievement_service 测试 (DTO 结构/序列化/map 构建)
- 新增 sticker_service 测试 (DTO 序列化/错误处理)
- 扩展 dto.rs 测试 (achievement/mood_stats/sticker/template/notification)
- 清理 2 个 unused import warning

验证:
- cargo check 0 error 0 warning
- flutter analyze 0 error

app/lib/features/mood/views/mood_page.dart

@@ -2,11 +2,13 @@
 
 import 'package:fl_chart/fl_chart.dart';
 import 'package:flutter/material.dart';
+import 'package:flutter_bloc/flutter_bloc.dart';
 import 'package:nuanji_app/core/theme/app_colors.dart';
 import 'package:nuanji_app/data/models/journal_entry.dart';
+import 'package:nuanji_app/data/remote/api_client.dart';
 import '../bloc/mood_bloc.dart';
 
-/// 心情页面 — 统计卡片 + 心情分布饼图 + 趋势折线图
+/// 心情页面 — 统计卡片 + 心情分布饼图 + 详情列表
 class MoodPage extends StatefulWidget {
   const MoodPage({super.key});
 
@@ -15,11 +17,12 @@ class MoodPage extends StatefulWidget {
 }
 
 class _MoodPageState extends State<MoodPage> {
-  final _bloc = MoodBloc();
+  late final MoodBloc _bloc;
 
   @override
   void initState() {
     super.initState();
+    _bloc = MoodBloc(api: context.read<ApiClient>());
     _bloc.load();
   }
 
@@ -43,6 +46,24 @@ class _MoodPageState extends State<MoodPage> {
           return const Center(child: CircularProgressIndicator());
         }
 
+        if (state.errorMessage != null) {
+          return Center(
+            child: Column(
+              mainAxisAlignment: MainAxisAlignment.center,
+              children: [
+                Icon(Icons.error_outline, size: 48, color: colorScheme.error),
+                const SizedBox(height: 12),
+                Text(state.errorMessage!, style: theme.textTheme.bodyMedium),
+                const SizedBox(height: 16),
+                FilledButton.tonal(
+                  onPressed: _bloc.load,
+                  child: const Text('重试'),
+                ),
+              ],
+            ),
+          );
+        }
+
         return SingleChildScrollView(
           padding: const EdgeInsets.all(16),
           child: Column(
@@ -207,7 +228,8 @@ class _MoodDistributionChart extends StatelessWidget {
           child: PieChart(
             PieChartData(
               sections: moodCounts.map((mc) {
-                final color = AppColors.moodColors[mc.mood.value] ?? colorScheme.primary;
+                final color =
+                    AppColors.moodColors[mc.mood.value] ?? colorScheme.primary;
                 return PieChartSectionData(
                   value: mc.count.toDouble(),
                   color: color,
@@ -239,7 +261,8 @@ class _MoodCountTile extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
     final theme = Theme.of(context);
-    final color = AppColors.moodColors[mc.mood.value] ?? theme.colorScheme.primary;
+    final color =
+        AppColors.moodColors[mc.mood.value] ?? theme.colorScheme.primary;
 
     return Padding(
       padding: const EdgeInsets.symmetric(vertical: 4),