Private notes are not filtered by account

The `requestPrivateNotes` endpoint does not filter for the active account when returning private notes.

Bug description
The wallet should separate private notes for the different accounts. Notes imported for the account A shouldn't be visible when the account B connected

How can this be reproduced?
Create the empty wallet A (an extension reinstall is required). Use the [miden faucet](https://faucet.testnet.miden.io/) to generate a private note and import it with the wallet UI or [demo app](https://demo.miden.fi/importPrivateNote)

Visit the [demo app](https://demo.miden.fi/privateNotes) with connected wallet A and request private notes with filter All. The single note should be visible.

Create the account B in the wallet UI. Disconnect the wallet A from the demo app and connect the wallet B. Refresh the page. Request the private notes again. The same note will be visible.

在代码库中找到 `requestPrivateNotes` 端点，很可能位于某个服务或 API 模块中。了解私有笔记的存储和检索方式，以及活动账户的识别方式。修复涉及在笔记检索逻辑中添加基于账户的过滤。使用演示应用重现 bug 描述中的步骤进行测试。

由索引模型根据 Issue 内容生成。