fix: 修复配额说明重复和undefined问题

- 在editStorageForm中初始化oss_storage_quota_value和oss_quota_unit
- 删除重复的旧配额说明块，保留新的当前配额设置显示

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/test_expire.js

@@ -0,0 +1,27 @@
+const { ShareDB } = require('./database');
+
+// 测试过期验证
+console.log('=== 测试分享过期验证 ===\n');
+
+// 获取所有分享
+const { db } = require('./database');
+const allShares = db.prepare('SELECT share_code, created_at, expires_at, datetime("now") as current_time FROM shares LIMIT 5').all();
+
+console.log('数据库中的分享:');
+allShares.forEach(share => {
+  console.log(`\n分享码: ${share.share_code}`);
+  console.log(`创建时间: ${share.created_at}`);
+  console.log(`到期时间: ${share.expires_at || '永久'}`);
+  console.log(`当前时间: ${share.current_time}`);
+
+  if (share.expires_at) {
+    const isExpired = share.expires_at <= share.current_time;
+    console.log(`是否过期: ${isExpired ? '是' : '否'}`);
+  }
+
+  // 测试findByCode
+  const found = ShareDB.findByCode(share.share_code);
+  console.log(`findByCode结果: ${found ? '找到' : '未找到(已过滤)'}`);
+});
+
+console.log('\n=== 测试完成 ===');