feat: 收藏夹系统 + Studio 趋势图 + 通知偏好设置

- 新增收藏夹系统 (Folder/FolderItem 模型、CRUD API、前端管理页)
- 新增文章详情页收藏按钮 (书签图标、ToggleFavorite 一键收藏)
- 新增 Studio 趋势图 (赋能值/评论/点赞/收藏 4 线图, 7d/30d/90d)
- 新增通知偏好设置页 (评论/回复/点赞/关注 4 类开关)
- 后端通知列表支持按偏好过滤 (排除已关闭的通知类型)
- 下载 Chart.js 到本地静态资源 (static/js/chart.umd.min.js)
- 补充收藏夹卡片、开关滑块、趋势图网格等 CSS 样式

internal/controller/settings_api_notify.go

@@ -0,0 +1,85 @@
+package controller
+
+import (
+	"net/http"
+
+	"metazone.cc/metalab/internal/common"
+	"metazone.cc/metalab/internal/model"
+
+	"github.com/gin-gonic/gin"
+)
+
+// notifyPrefReader 通知偏好读写的接口（ISP）
+type notifyPrefReader interface {
+	GetNotifyPrefs(userID uint) (map[string]bool, error)
+	UpdateNotifyPref(userID uint, key string, enabled bool) error
+}
+
+// SetNotifyPrefReader 注入通知偏好读写器
+func (sc *SettingsController) SetNotifyPrefReader(reader notifyPrefReader) {
+	sc.notifyPrefReader = reader
+}
+
+// GetNotifyPrefs 获取通知偏好 GET /api/settings/notify-prefs
+func (sc *SettingsController) GetNotifyPrefs(c *gin.Context) {
+	uid, exists := c.Get("uid")
+	if !exists {
+		common.Error(c, http.StatusUnauthorized, "请先登录")
+		return
+	}
+
+	if sc.notifyPrefReader == nil {
+		common.Error(c, http.StatusInternalServerError, "服务不可用")
+		return
+	}
+
+	prefs, err := sc.notifyPrefReader.GetNotifyPrefs(uid.(uint))
+	if err != nil {
+		common.Error(c, http.StatusInternalServerError, "获取失败")
+		return
+	}
+
+	common.Ok(c, prefs)
+}
+
+// UpdateNotifyPref 更新通知偏好 PUT /api/settings/notify-prefs
+func (sc *SettingsController) UpdateNotifyPref(c *gin.Context) {
+	uid, exists := c.Get("uid")
+	if !exists {
+		common.Error(c, http.StatusUnauthorized, "请先登录")
+		return
+	}
+
+	if sc.notifyPrefReader == nil {
+		common.Error(c, http.StatusInternalServerError, "服务不可用")
+		return
+	}
+
+	var req struct {
+		Key     string `json:"key"`
+		Enabled bool   `json:"enabled"`
+	}
+	if err := c.ShouldBindJSON(&req); err != nil {
+		common.Error(c, http.StatusBadRequest, "参数错误")
+		return
+	}
+
+	// 验证 key 是否合法
+	allowedKeys := map[string]bool{
+		model.NotifyComment:        true,
+		model.NotifyCommentReply:   true,
+		model.NotifyLikeAggregated: true,
+		model.NotifyFollow:         true,
+	}
+	if !allowedKeys[req.Key] {
+		common.Error(c, http.StatusBadRequest, "无效的通知类型")
+		return
+	}
+
+	if err := sc.notifyPrefReader.UpdateNotifyPref(uid.(uint), req.Key, req.Enabled); err != nil {
+		common.Error(c, http.StatusInternalServerError, "更新失败")
+		return
+	}
+
+	common.OkMessage(c, "通知偏好已更新")
+}