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/templates/bloc/template_bloc.dart

@@ -0,0 +1,135 @@
+// 模板 BLoC — 通过 API 加载模板列表
+
+import 'package:flutter/material.dart';
+import 'package:nuanji_app/data/remote/api_client.dart';
+
+// ===== 模型 =====
+
+/// 日记模板
+class Template {
+  final String id;
+  final String name;
+  final String? description;
+  final String? previewUrl;
+  final Map<String, dynamic>? templateData;
+  final String? category;
+  final bool isFree;
+
+  /// 用于 UI 显示的 emoji（基于 category 推导）
+  String get emoji => switch (category) {
+        '日常' => '☀️',
+        '旅行' => '🗺️',
+        '校园' => '📚',
+        '节日' => '🎄',
+        '创意' => '✨',
+        _ => '📝',
+      };
+
+  const Template({
+    required this.id,
+    required this.name,
+    this.description,
+    this.previewUrl,
+    this.templateData,
+    this.category,
+    this.isFree = true,
+  });
+}
+
+// ===== State =====
+
+/// 模板页面状态
+class TemplateState {
+  final List<Template> templates;
+  final String selectedCategory;
+  final bool isLoading;
+  final String? errorMessage;
+
+  const TemplateState({
+    this.templates = const [],
+    this.selectedCategory = '全部',
+    this.isLoading = false,
+    this.errorMessage,
+  });
+
+  /// 按分类过滤模板
+  List<Template> get filteredTemplates => selectedCategory == '全部'
+      ? templates
+      : templates.where((t) => t.category == selectedCategory).toList();
+
+  /// 所有分类（去重 + 加"全部"）
+  List<String> get categories {
+    final cats = templates
+        .map((t) => t.category)
+        .whereType<String>()
+        .toSet()
+        .toList();
+    return ['全部', ...cats];
+  }
+
+  TemplateState copyWith({
+    List<Template>? templates,
+    String? selectedCategory,
+    bool? isLoading,
+    String? errorMessage,
+  }) =>
+      TemplateState(
+        templates: templates ?? this.templates,
+        selectedCategory: selectedCategory ?? this.selectedCategory,
+        isLoading: isLoading ?? this.isLoading,
+        errorMessage: errorMessage,
+      );
+}
+
+// ===== BLoC =====
+
+/// 模板 BLoC — ChangeNotifier 模式
+class TemplateBloc extends ChangeNotifier {
+  final ApiClient _api;
+  TemplateState _state = const TemplateState();
+  TemplateState get state => _state;
+
+  TemplateBloc({required ApiClient api}) : _api = api;
+
+  /// 加载模板列表
+  void load() {
+    _state = _state.copyWith(isLoading: true);
+    notifyListeners();
+    _fetchTemplates();
+  }
+
+  /// 选择分类
+  void selectCategory(String category) {
+    _state = _state.copyWith(selectedCategory: category);
+    notifyListeners();
+  }
+
+  Future<void> _fetchTemplates() async {
+    try {
+      final response = await _api.get('/diary/templates');
+      final body = response.data as Map<String, dynamic>;
+      final list = body['data'] as List? ?? [];
+
+      final templates = list.map((item) {
+        final m = item as Map<String, dynamic>;
+        return Template(
+          id: m['id'] as String,
+          name: m['name'] as String,
+          description: m['description'] as String?,
+          previewUrl: m['preview_url'] as String?,
+          templateData: m['template_data'] as Map<String, dynamic>?,
+          category: m['category'] as String?,
+          isFree: m['is_free'] as bool? ?? true,
+        );
+      }).toList();
+
+      _state = _state.copyWith(isLoading: false, templates: templates);
+    } catch (e) {
+      _state = _state.copyWith(
+        isLoading: false,
+        errorMessage: '加载模板列表失败',
+      );
+    }
+    notifyListeners();
+  }
+}

app/lib/features/templates/views/template_gallery_page.dart

@@ -1,27 +1,11 @@
 // 模板画廊页面 — 日记模板浏览和选择
 
 import 'package:flutter/material.dart';
+import 'package:flutter_bloc/flutter_bloc.dart';
 import 'package:go_router/go_router.dart';
 import 'package:nuanji_app/core/theme/app_colors.dart';
-
-/// 模板数据模型
-class Template {
-  final String id;
-  final String name;
-  final String emoji;
-  final String? category;
-  final bool isFree;
-  final String? description;
-
-  const Template({
-    required this.id,
-    required this.name,
-    required this.emoji,
-    this.category,
-    this.isFree = true,
-    this.description,
-  });
-}
+import 'package:nuanji_app/data/remote/api_client.dart';
+import '../bloc/template_bloc.dart';
 
 /// 模板画廊页面 — 浏览和选择日记模板
 class TemplateGalleryPage extends StatefulWidget {
@@ -32,81 +16,104 @@ class TemplateGalleryPage extends StatefulWidget {
 }
 
 class _TemplateGalleryPageState extends State<TemplateGalleryPage> {
-  String _selectedCategory = '全部';
+  late final TemplateBloc _bloc;
 
-  final _categories = ['全部', '日常', '旅行', '校园', '节日', '创意'];
+  @override
+  void initState() {
+    super.initState();
+    _bloc = TemplateBloc(api: context.read<ApiClient>());
+    _bloc.load();
+  }
 
-  // Phase 1 占位数据
-  final _templates = const [
-    Template(id: '1', name: '今日心情', emoji: '💭', category: '日常', description: '记录今天的心情和感受'),
-    Template(id: '2', name: '校园日记', emoji: '📚', category: '校园', description: '在学校的一天'),
-    Template(id: '3', name: '旅行手账', emoji: '🗺️', category: '旅行', description: '记录旅行中的美好瞬间'),
-    Template(id: '4', name: '美食记录', emoji: '🍜', category: '日常', description: '记录今天吃到的美食'),
-    Template(id: '5', name: '读书笔记', emoji: '📖', category: '校园', description: '记录读完一本书的感想'),
-    Template(id: '6', name: '节日特辑', emoji: '🎄', category: '节日', description: '特别的节日记录'),
-    Template(id: '7', name: '自然观察', emoji: '🌿', category: '创意', description: '记录大自然的发现'),
-    Template(id: '8', name: '梦想清单', emoji: '✨', category: '创意', description: '写下心中的梦想'),
-    Template(id: '9', name: '周末时光', emoji: '☀️', category: '日常', description: '悠闲的周末记录'),
-    Template(id: '10', name: '运动打卡', emoji: '🏃', category: '日常', description: '记录运动和锻炼'),
-  ];
+  @override
+  void dispose() {
+    _bloc.dispose();
+    super.dispose();
+  }
 
   @override
   Widget build(BuildContext context) {
     final theme = Theme.of(context);
     final colorScheme = theme.colorScheme;
 
-    final filtered = _selectedCategory == '全部'
-        ? _templates
-        : _templates.where((t) => t.category == _selectedCategory).toList();
-
     return Scaffold(
-      appBar: AppBar(
-        title: const Text('模板画廊'),
-      ),
-      body: Column(
-        children: [
-          // 分类选择器
-          SizedBox(
-            height: 48,
-            child: ListView(
-              scrollDirection: Axis.horizontal,
-              padding: const EdgeInsets.symmetric(horizontal: 16),
-              children: _categories.map((cat) {
-                final isSelected = cat == _selectedCategory;
-                return Padding(
-                  padding: const EdgeInsets.only(right: 8),
-                  child: FilterChip(
-                    selected: isSelected,
-                    label: Text(cat),
-                    onSelected: (_) {
-                      setState(() => _selectedCategory = cat);
-                    },
-                    selectedColor: colorScheme.primaryContainer,
-                    checkmarkColor: colorScheme.primary,
-                  ),
-                );
-              }).toList(),
-            ),
-          ),
-          const SizedBox(height: 8),
+      appBar: AppBar(title: const Text('模板画廊')),
+      body: ListenableBuilder(
+        listenable: _bloc,
+        builder: (context, _) {
+          final state = _bloc.state;
 
-          // 模板网格
-          Expanded(
-            child: GridView.builder(
-              padding: const EdgeInsets.all(16),
-              gridDelegate: const SliverGridDelegateWithFixedCrossAxisCount(
-                crossAxisCount: 2,
-                mainAxisSpacing: 12,
-                crossAxisSpacing: 12,
-                childAspectRatio: 0.78,
+          if (state.isLoading) {
+            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: 16),
+                  FilledButton.tonal(
+                    onPressed: _bloc.load,
+                    child: const Text('重试'),
+                  ),
+                ],
               ),
-              itemCount: filtered.length,
-              itemBuilder: (context, index) {
-                return _TemplateCard(template: filtered[index]);
-              },
-            ),
-          ),
-        ],
+            );
+          }
+
+          final categories = state.categories;
+
+          return Column(
+            children: [
+              // 分类选择器
+              SizedBox(
+                height: 48,
+                child: ListView(
+                  scrollDirection: Axis.horizontal,
+                  padding: const EdgeInsets.symmetric(horizontal: 16),
+                  children: categories.map((cat) {
+                    final isSelected = cat == state.selectedCategory;
+                    return Padding(
+                      padding: const EdgeInsets.only(right: 8),
+                      child: FilterChip(
+                        selected: isSelected,
+                        label: Text(cat),
+                        onSelected: (_) => _bloc.selectCategory(cat),
+                        selectedColor: colorScheme.primaryContainer,
+                        checkmarkColor: colorScheme.primary,
+                      ),
+                    );
+                  }).toList(),
+                ),
+              ),
+              const SizedBox(height: 8),
+
+              // 模板网格
+              Expanded(
+                child: state.filteredTemplates.isEmpty
+                    ? const Center(child: Text('暂无模板'))
+                    : GridView.builder(
+                        padding: const EdgeInsets.all(16),
+                        gridDelegate:
+                            const SliverGridDelegateWithFixedCrossAxisCount(
+                          crossAxisCount: 2,
+                          mainAxisSpacing: 12,
+                          crossAxisSpacing: 12,
+                          childAspectRatio: 0.78,
+                        ),
+                        itemCount: state.filteredTemplates.length,
+                        itemBuilder: (context, index) {
+                          return _TemplateCard(
+                            template: state.filteredTemplates[index],
+                          );
+                        },
+                      ),
+              ),
+            ],
+          );
+        },
       ),
     );
   }