feat: 文章属性前端完成 — Phase 3

- 写文章页：可见性/类型/转载来源/创作声明/禁止转载 属性表单
- 类型切换联动（转载显示来源，原创显示禁止转载复选框）
- 文章详情页：私密角标、置顶标记、创作声明横幅、转载来源
- 管理后台：置顶/取消置顶操作按钮
- PostService Create/Update 签名扩展接受文章属性
- DTO/接口同步更新

templates/MetaLab-2026/html/posts/show.html

@@ -18,6 +18,12 @@
                 <span>收藏：{{.Post.FavoritesCount}}</span>
                 <span>评论：{{.Post.CommentsCount}}</span>
                 <span>发布时间：{{.Post.CreatedAt.Format "2006-01-02 15:04"}}</span>
+                {{if eq .Post.Visibility "private"}}
+                <span class="post-badge post-badge-private">私密</span>
+                {{end}}
+                {{if .Post.PinType}}
+                <span class="post-badge post-badge-pinned">📌 {{if eq .Post.PinType "global"}}全局置顶{{else}}分类置顶{{end}}</span>
+                {{end}}
                 {{if and .Post.IsLocked (eq $.Post.UserID $.UID)}}
                 <span class="post-status post-status-locked">已锁定{{if .Post.LockReason}}：{{.Post.LockReason}}{{end}}</span>
                 {{end}}
@@ -25,6 +31,19 @@
                 <span class="post-status post-status-revision">修订审核中</span>
                 {{end}}
             </div>
+            <!-- 文章属性声明 -->
+            {{if or .Post.Declaration .Post.ReprintSource .Post.ReprintProhibited (eq .Post.PostType "reprint")}}
+            <div class="post-declarations">
+                {{if .Post.Declaration}}
+                <div class="post-declaration-item">⚡ {{declarationLabel .Post.Declaration}}</div>
+                {{end}}
+                {{if eq .Post.PostType "reprint"}}
+                <div class="post-declaration-item">📎 转载自：{{.Post.ReprintSource}}</div>
+                {{else if .Post.ReprintProhibited}}
+                <div class="post-declaration-item">⚠ 未经作者许可，禁止转载</div>
+                {{end}}
+            </div>
+            {{end}}
         </header>
 
         {{if .Post.RejectReason}}