fix: 套餐和密钥只能新增不能删除

[webbrain-one]

Closes #4

[aa2013]

Thanks for the contribution!

I reviewed the changes, but this PR does not fully implement delete support yet. It currently only adds frontend-side buttons/API wrappers.

Main issues:

1. There are no backend routes for the new requests:

   • POST /admin/plan/delete
   • POST /admin/planKeys/delete

   The current backend only registers add/edit/list/updateStatus/generate/list/verify endpoints, so these delete requests will fail.

2. There are no DB-layer delete methods for plans or plan keys.
   We would need something like:

   • DeletePlan(id string)
   • DeletePlanKey(id int)

3. The plan key delete API wrapper is added, but it does not appear to be used in the plan key table UI. The key list page still only has view/status actions.

4. Deleting plans probably needs additional business logic:

   • Should plan keys under that plan be deleted too?
   • Should enabled plans be blocked from deletion?
   • Should active connections using deleted keys be disconnected?
   • Should related caches be refreshed?

So I don’t think this PR is ready to merge yet. Could you please add the backend implementation and wire up the plan key delete UI as well?

---

感谢贡献！

我看了一下，这个 PR 目前还没有完整实现删除功能，主要只是加了前端按钮和请求封装。

目前的问题是：

1. 后端没有对应的删除接口：

   • /admin/plan/delete
   • /admin/planKeys/delete

2. DB 层也没有删除套餐或删除密钥的方法。

3. deletePlanKey 这个前端请求方法虽然加了，但密钥列表页面里没有删除按钮，也没有实际调用它。

4. 删除套餐还需要考虑一些业务逻辑，比如是否级联删除套餐下的密钥、启用中的套餐是否允许删除、在线连接是否需要断开等。

所以这个 PR 现在还不能合并。麻烦补齐后端接口、数据库删除逻辑，以及密钥删除的前端交互后再更新一下。