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

crates/erp-diary/src/dto.rs

@@ -430,4 +430,140 @@ mod tests {
         let json = serde_json::to_string(&resp).unwrap();
         assert!(json.contains("\"is_active\":true"));
     }
+
+    #[test]
+    fn achievement_resp_serializes() {
+        let resp = AchievementResp {
+            id: uuid::Uuid::nil(),
+            code: "first_diary".into(),
+            name: "初次落笔".into(),
+            description: Some("写下第一篇日记".into()),
+            icon: Some("✏️".into()),
+            category: "writing".into(),
+            is_unlocked: true,
+            unlocked_at: None,
+        };
+        let json = serde_json::to_string(&resp).unwrap();
+        assert!(json.contains("\"code\":\"first_diary\""));
+        assert!(json.contains("\"is_unlocked\":true"));
+    }
+
+    #[test]
+    fn achievement_resp_unlocked_at_present() {
+        let now = chrono::Utc::now();
+        let resp = AchievementResp {
+            id: uuid::Uuid::nil(),
+            code: "streak_7".into(),
+            name: "坚持一周".into(),
+            description: None,
+            icon: None,
+            category: "writing".into(),
+            is_unlocked: true,
+            unlocked_at: Some(now),
+        };
+        let json = serde_json::to_string(&resp).unwrap();
+        assert!(json.contains("unlocked_at"));
+    }
+
+    #[test]
+    fn mood_stats_resp_structure() {
+        let resp = MoodStatsResp {
+            mood_counts: vec![
+                MoodCount {
+                    mood: Mood::Happy,
+                    count: 12,
+                    percentage: 60.0,
+                },
+                MoodCount {
+                    mood: Mood::Calm,
+                    count: 8,
+                    percentage: 40.0,
+                },
+            ],
+            streak_days: 7,
+            total_journals: 20,
+            dominant_mood: Some(Mood::Happy),
+        };
+        let json = serde_json::to_string(&resp).unwrap();
+        assert!(json.contains("\"streak_days\":7"));
+        assert!(json.contains("\"total_journals\":20"));
+        assert!(json.contains("\"dominant_mood\":\"happy\""));
+    }
+
+    #[test]
+    fn sticker_resp_fields() {
+        let resp = StickerResp {
+            id: uuid::Uuid::nil(),
+            pack_id: uuid::Uuid::nil(),
+            name: "笑脸".into(),
+            image_url: "https://cdn.example.com/smile.png".into(),
+            category: Some("表情".into()),
+        };
+        let json = serde_json::to_string(&resp).unwrap();
+        assert!(json.contains("\"image_url\""));
+        assert!(json.contains("\"category\":\"表情\""));
+    }
+
+    #[test]
+    fn template_resp_with_layout_data() {
+        let resp = TemplateResp {
+            id: uuid::Uuid::nil(),
+            name: "校园日记".into(),
+            description: Some("在学校的一天".into()),
+            preview_url: Some("https://cdn.example.com/preview.png".into()),
+            template_data: Some(serde_json::json!({
+                "sections": [{"type": "title"}, {"type": "body"}]
+            })),
+            category: Some("校园".into()),
+            is_free: true,
+        };
+        let json = serde_json::to_string(&resp).unwrap();
+        assert!(json.contains("\"sections\""));
+        assert!(json.contains("\"preview_url\""));
+    }
+
+    #[test]
+    fn create_journal_req_with_class() {
+        let json = r#"{
+            "title": "班级日记",
+            "date": "2026-06-01",
+            "mood": "happy",
+            "weather": "sunny",
+            "tags": ["校园"],
+            "is_private": false,
+            "class_id": "00000000-0000-0000-0000-000000000001"
+        }"#;
+        let req: CreateJournalReq = serde_json::from_str(json).unwrap();
+        assert!(!req.is_private);
+        assert!(req.class_id.is_some());
+    }
+
+    #[test]
+    fn join_class_req() {
+        let json = r#"{"class_code": "ABC123"}"#;
+        let req: JoinClassReq = serde_json::from_str(json).unwrap();
+        assert_eq!(req.class_code, "ABC123");
+    }
+
+    #[test]
+    fn create_class_req() {
+        let json = r#"{"name": "三年二班", "school_name": "阳光小学"}"#;
+        let req: CreateClassReq = serde_json::from_str(json).unwrap();
+        assert_eq!(req.name, "三年二班");
+        assert_eq!(req.school_name, Some("阳光小学".into()));
+    }
+
+    #[test]
+    fn notification_payload_structure() {
+        let payload = NotificationPayload {
+            notification_type: NotificationType::AchievementUnlocked,
+            recipient_id: uuid::Uuid::nil(),
+            title: "成就解锁".into(),
+            body: "你解锁了「初次落笔」成就".into(),
+            business_id: Some(uuid::Uuid::nil()),
+            extra: None,
+        };
+        let json = serde_json::to_string(&payload).unwrap();
+        assert!(json.contains("\"notification_type\":\"achievement_unlocked\""));
+    }
 }