fix: 修复媒体文件路径缺失目录前缀 & WebUI 请求历史改进 (ref #70)

- 修复媒体文件服务接口未拼接 mediaDir 导致图片无法显示的问题
- 历史模块路径改为绝对路径，与 config 模块保持一致
- Prompt 列支持点击弹窗预览完整内容
- 预览弹窗新增「复制全文」按钮
- 重发失败记录时自动删除旧的失败条目

src/server/api/admin/routes.js

@@ -43,7 +43,8 @@ import {
     deleteByDateRange as deleteHistoryByDateRange,
     retryMediaDownload,
     getStats as getHistoryStats,
-    getModelList as getHistoryModelList
+    getModelList as getHistoryModelList,
+    getMediaDir
 } from '../../../utils/history.js';
 import path from 'path';
 import fs from 'fs/promises';
@@ -519,7 +520,8 @@ export function createAdminRouter(context) {
                 }
 
                 try {
-                    const data = await fs.readFile(filepath);
+                    const fullPath = path.join(getMediaDir(), filepath);
+                    const data = await fs.readFile(fullPath);
                     const ext = path.extname(filepath).toLowerCase();
                     const mimeTypes = {
                         '.png': 'image/png',

src/utils/history.js

@@ -8,7 +8,7 @@ import fs from 'fs/promises';
 import path from 'path';
 import { logger } from './logger.js';
 
-const DATA_DIR = 'data/history';
+const DATA_DIR = path.join(process.cwd(), 'data', 'history');
 const DB_PATH = path.join(DATA_DIR, 'history.db');
 const MEDIA_DIR = path.join(DATA_DIR, 'media');