User management through UI with a SQLite DB

**is your feature request related to a problem? Please describe.**

I have some less technical users and I want them to be able to reset their own password.

**Describe the idea / solution you'd like**

User management through the UI, with self-serve password reset and signup, ideally with just a simple sqlite DB for simplicity.

**Describe any alternatives you've considered**

Using something like Keycloak and `forward_auth` for SSO but I don't think that would work here either and is a very heavyweight solution.

該 issue 要求使用 SQLite 實作一個使用者管理 UI，並支援使用者自行重設密碼和註冊。首先檢查 copyparty 中現有的驗證和使用者儲存程式碼。尋找與使用者登入和工作階段管理相關的路由或處理常式。確定如何新增用於使用者註冊和密碼重設的 UI 頁面及後端端點，同時確保與目前 SQLite 設定整合。檢查是否已有可以擴充的範本或前端元件。

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