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/admin/static/js/common.js

@@ -37,36 +37,6 @@ const api = {
     }
 };
 
-// --- 确认弹窗 ---
-function showConfirm(title, message) {
-    return new Promise((resolve) => {
-        const overlay = document.createElement('div');
-        overlay.className = 'modal-overlay show';
-        overlay.innerHTML = `
-            <div class="modal-box">
-                <h3>${escapeHtml(title)}</h3>
-                <p>${escapeHtml(message)}</p>
-                <div class="modal-actions">
-                    <button class="btn btn-outline" id="modalCancel">取消</button>
-                    <button class="btn btn-danger" id="modalConfirm">确认</button>
-                </div>
-            </div>`;
-        document.body.appendChild(overlay);
-
-        overlay.querySelector('#modalCancel').onclick = () => {
-            overlay.remove();
-            resolve(false);
-        };
-        overlay.querySelector('#modalConfirm').onclick = () => {
-            overlay.remove();
-            resolve(true);
-        };
-        overlay.addEventListener('click', (e) => {
-            if (e.target === overlay) { overlay.remove(); resolve(false); }
-        });
-    });
-}
-
 // --- 角色标签 ---
 // 数据源由服务端 model.RoleDisplayNames 注入为 window.__ROLE_NAMES
 function roleLabel(role) {