feat: prompt/confirm 替换为自定义弹窗

- shared/utils.js 新增 showConfirm()/showPrompt() 通用函数（inline CSS，无需额外样式）
- admin/common.js 移除重复 showConfirm()，统一使用 utils.js
- admin/posts.js: 3 处 confirm/prompt 替换（审核/退回/锁定）
- admin/comments.js: 1 处 confirm 替换
- settings/index.html: 4 处 confirm + 1 处 prompt 替换
- studio/posts.html + drafts.html: 3 处 confirm 替换
- post-view.js + login.js + post-favorite.js: 3 处 confirm 替换

templates/MetaLab-2026/static/js/post-favorite.js

@@ -119,21 +119,23 @@
 
     function removeFromFolder(folderId) {
         if (loading) return;
-        if (!confirm('确定取消收藏吗？')) return;
-        loading = true;
-        api('DELETE', '/api/folders/' + folderId + '/posts/' + postId)
-            .then(function(d) {
-                loading = false;
-                if (d.success) {
-                    currentFolderId = null;
-                    updateBtn(false);
-                    if (favCountEl) favCountEl.textContent = Math.max(0, (parseInt(favCountEl.textContent) || 0) - 1);
-                    hideModal();
-                } else {
+        showConfirm('确认', '确定取消收藏吗？').then(function(ok) {
+            if (!ok) return;
+            loading = true;
+            api('DELETE', '/api/folders/' + folderId + '/posts/' + postId)
+                .then(function(d) {
+                    loading = false;
+                    if (d.success) {
+                        currentFolderId = null;
+                        updateBtn(false);
+                        if (favCountEl) favCountEl.textContent = Math.max(0, (parseInt(favCountEl.textContent) || 0) - 1);
+                        hideModal();
+                    } else {
                     alert(d.message || '操作失败');
                 }
             })
             .catch(function() { loading = false; });
+        });
     }
 
     function createAndAdd(name) {