feat: 新增备份恢复功能 & 改进图片上传体验

- 新增备份管理页面（备份/恢复/下载/删除）
- 新增 backup_service 服务层
- 文章编辑器增加工具栏图片上传按钮
- 优化图片上传交互提示

app/routes/admin/__init__.py

@@ -17,4 +17,4 @@ def login_required(f):
 
 
 # 导入子模块以注册路由
-from app.routes.admin import auth, dashboard, articles, categories, tags, settings, stats, upload, authors
+from app.routes.admin import auth, dashboard, articles, categories, tags, settings, stats, upload, authors, backup

app/routes/admin/backup.py

@@ -0,0 +1,68 @@
+"""备份管理路由"""
+from flask import render_template, request, jsonify, send_file
+from app.routes.admin import admin_bp, login_required
+from app.services.backup_service import BackupService
+
+
+@admin_bp.route('/backup')
+@login_required
+def backup_page():
+    """备份管理页面"""
+    backups = BackupService.list_backups()
+    
+    stats = {
+        'total_backups': len(backups),
+        'total_size': sum(b['size'] for b in backups)
+    }
+    
+    return render_template('admin/backup.html', backups=backups, stats=stats)
+
+
+@admin_bp.route('/backup/create', methods=['POST'])
+@login_required
+def backup_create():
+    """创建备份"""
+    include_uploads = request.form.get('include_uploads', 'true').lower() == 'true'
+    
+    result, error = BackupService.create_backup(include_uploads=include_uploads)
+    
+    if error:
+        return jsonify({'success': False, 'message': error}), 400
+    
+    return jsonify({
+        'success': True,
+        'backup': {
+            'filename': result['filename'],
+            'size': BackupService.format_filesize(result['size']),
+            'timestamp': result['timestamp']
+        }
+    })
+
+
+@admin_bp.route('/backup/download/<filename>')
+@login_required
+def backup_download(filename):
+    """下载备份文件"""
+    filepath = BackupService.get_backup_path(filename)
+    
+    import os
+    if not os.path.exists(filepath):
+        return jsonify({'success': False, 'message': '备份文件不存在'}), 404
+    
+    return send_file(
+        filepath,
+        as_attachment=True,
+        download_name=filename
+    )
+
+
+@admin_bp.route('/backup/delete/<filename>', methods=['POST'])
+@login_required
+def backup_delete(filename):
+    """删除备份文件"""
+    success, error = BackupService.delete_backup(filename)
+    
+    if not success:
+        return jsonify({'success': False, 'message': error}), 400
+    
+    return jsonify({'success': True})