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/html/posts/show.html

@@ -31,7 +31,7 @@
         <div class="post-detail-body" id="postContent"></div>
     </article>
 
-    <!-- 赞/踩按钮 -->
+    <!-- 赞/踩/收藏按钮 -->
     <div class="post-reactions" id="postReactions" data-post-id="{{.Post.ID}}">
         <button class="reaction-btn reaction-like-btn" id="likeBtn" title="点赞">
             <svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" width="20" height="20"><path d="M14 9V5a3 3 0 0 0-3-3l-4 9v11h11.28a2 2 0 0 0 2-1.7l1.38-9a2 2 0 0 0-2-2.3H14zM7 22H4a2 2 0 0 1-2-2v-7a2 2 0 0 1 2-2h3"/></svg>
@@ -40,6 +40,10 @@
         <button class="reaction-btn reaction-dislike-btn" id="dislikeBtn" title="踩">
             <svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" width="20" height="20"><path d="M10 15v4a3 3 0 0 0 3 3l4-9V2H5.72a2 2 0 0 0-2 1.7l-1.38 9a2 2 0 0 0 2 2.3H10zM17 2h2.67A2.31 2.31 0 0 1 22 4v7a2.31 2.31 0 0 1-2.33 2H17"/></svg>
         </button>
+        <button class="reaction-btn reaction-fav-btn" id="favBtn" title="收藏">
+            <svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" width="20" height="20"><path d="M19 21l-7-5-7 5V5a2 2 0 0 1 2-2h10a2 2 0 0 1 2 2z"/></svg>
+            <span class="reaction-like-count" id="favCount">{{.Post.FavoritesCount}}</span>
+        </button>
     </div>
 
     {{if .IsLoggedIn}}
@@ -340,6 +344,63 @@
 })();
 </script>
 
+<script>
+// ========== 收藏按钮 ==========
+(function() {
+    var favBtn = document.getElementById('favBtn');
+    var favCountEl = document.getElementById('favCount');
+    var container = document.getElementById('postReactions');
+    if (!favBtn || !container) return;
+
+    var postId = container.dataset.postId;
+    var csrfMeta = document.querySelector('meta[name="csrf-token"]');
+    var csrfToken = csrfMeta ? csrfMeta.getAttribute('content') : '';
+
+    // 页面加载时获取收藏状态
+    fetch('/api/posts/' + postId + '/folder-status')
+        .then(function(r) { return r.json(); })
+        .then(function(d) {
+            if (d.success && d.data && d.data.favorited) {
+                favBtn.classList.add('active');
+            }
+        })
+        .catch(function() {});
+
+    favBtn.addEventListener('click', function() {
+        favBtn.disabled = true;
+        fetch('/api/posts/' + postId + '/favorite', {
+            method: 'POST',
+            headers: { 'Content-Type': 'application/json', 'X-CSRF-Token': csrfToken }
+        })
+        .then(function(r) {
+            if (r.status === 401) { window.location.href = '/login?redirect=/posts/' + postId; return null; }
+            return r.json();
+        })
+        .then(function(d) {
+            favBtn.disabled = false;
+            if (!d) return;
+            if (d.success) {
+                var isFav = d.data && d.data.favorited;
+                if (isFav) {
+                    favBtn.classList.add('active');
+                } else {
+                    favBtn.classList.remove('active');
+                }
+                if (favCountEl && d.data && typeof d.data.favorites_count === 'number') {
+                    favCountEl.textContent = d.data.favorites_count;
+                } else if (favCountEl) {
+                    var cur = parseInt(favCountEl.textContent) || 0;
+                    favCountEl.textContent = isFav ? cur + 1 : Math.max(0, cur - 1);
+                }
+            } else {
+                alert(d.message || '操作失败');
+            }
+        })
+        .catch(function() { favBtn.disabled = false; });
+    });
+})();
+</script>
+
 <script>
 // ========== 评论系统 ==========
 (function() {