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

templates/MetaLab-2026/static/css/settings.css

@@ -877,3 +877,139 @@ body {
 .energy-log-minus .energy-log-amount {
     color: #e74c3c;
 }
+
+/* ---------- 收藏夹 Tab ---------- */
+.fav-toolbar {
+    margin-bottom: 1rem;
+}
+
+.fav-list {
+    display: flex;
+    flex-direction: column;
+    gap: 0;
+}
+
+.fav-folder-card {
+    display: flex;
+    justify-content: space-between;
+    align-items: center;
+    padding: 1rem 0;
+    border-bottom: 1px solid #f0f0f0;
+}
+
+.fav-folder-card:last-child {
+    border-bottom: none;
+}
+
+.fav-folder-info {
+    display: flex;
+    flex-direction: column;
+    gap: .25rem;
+}
+
+.fav-folder-name {
+    font-size: .95rem;
+    font-weight: 600;
+    color: var(--color-text);
+}
+
+.fav-folder-meta {
+    font-size: .8rem;
+    color: var(--color-text-light);
+}
+
+.fav-folder-actions {
+    flex-shrink: 0;
+}
+
+.fav-folder-del {
+    padding: .35rem .75rem;
+    font-size: .78rem;
+    font-weight: 500;
+    font-family: inherit;
+    color: #e74c3c;
+    background: #fff5f5;
+    border: 1px solid #fecaca;
+    border-radius: 5px;
+    cursor: pointer;
+    transition: all .15s ease;
+}
+
+.fav-folder-del:hover {
+    background: #fee2e2;
+    border-color: #e74c3c;
+}
+
+/* ---------- 通知偏好 Tab ---------- */
+.notify-pref-row {
+    display: flex;
+    justify-content: space-between;
+    align-items: center;
+    padding: 1rem 0;
+    border-bottom: 1px solid #f0f0f0;
+}
+
+.notify-pref-row:last-child {
+    border-bottom: none;
+}
+
+.notify-pref-info {
+    display: flex;
+    flex-direction: column;
+    gap: .2rem;
+}
+
+.notify-pref-label {
+    font-size: .92rem;
+    font-weight: 600;
+    color: var(--color-text);
+}
+
+.notify-pref-desc {
+    font-size: .8rem;
+    color: var(--color-text-light);
+}
+
+.notify-pref-toggle {
+    position: relative;
+    display: inline-block;
+    width: 44px;
+    height: 24px;
+    flex-shrink: 0;
+}
+
+.notify-pref-toggle input {
+    opacity: 0;
+    width: 0;
+    height: 0;
+}
+
+.notify-pref-slider {
+    position: absolute;
+    cursor: pointer;
+    inset: 0;
+    background: #d1d5db;
+    border-radius: 24px;
+    transition: background .2s ease;
+}
+
+.notify-pref-slider::before {
+    content: '';
+    position: absolute;
+    height: 18px;
+    width: 18px;
+    left: 3px;
+    bottom: 3px;
+    background: #fff;
+    border-radius: 50%;
+    transition: transform .2s ease;
+    box-shadow: 0 1px 3px rgba(0,0,0,.15);
+}
+
+.notify-pref-toggle input:checked + .notify-pref-slider {
+    background: var(--color-accent);
+}
+
+.notify-pref-toggle input:checked + .notify-pref-slider::before {
+    transform: translateX(20px);
+}