feat(webui): enable Range request support for backup downloads

[RC-CHN]

修复了 #4294 ，解决了较大的备份文件下载时出现的问题

Modifications / 改动点

添加conditional参数为备份下载启用断点续传

• This is NOT a breaking change. / 这不是一个破坏性变更。

Screenshots or Test Results / 运行截图或测试结果

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Checklist / 检查清单

• 😊 如果 PR 中有新加入的功能，已经通过 Issue / 邮件等方式和作者讨论过。/ If there are new features added in the PR, I have discussed it with the authors through issues/emails, etc.
• 👀 我的更改经过了良好的测试，并已在上方提供了“验证步骤”和“运行截图”。/ My changes have been well-tested, and "Verification Steps" and "Screenshots" have been provided above.
• 🤓 我确保没有引入新依赖库，或者引入了新依赖库的同时将其添加到了 requirements.txt 和 pyproject.toml 文件相应位置。/ I have ensured that no new dependencies are introduced, OR if new dependencies are introduced, they have been added to the appropriate locations in requirements.txt and pyproject.toml.
• 😮 我的更改没有引入恶意代码。/ My changes do not introduce malicious code.

Summary by Sourcery

Bug Fixes:

• 通过支持使用 Range 请求恢复中断的下载，解决在下载大型备份文件时出现的不稳定和失败问题。

Original summary in English

Summary by Sourcery

Bug Fixes:

• Resolve instability and failures when downloading large backup files by allowing interrupted downloads to be resumed via Range requests.

- 通过允许客户端使用 Range 请求恢复中断的备份下载，修复了大型备份文件下载失败或不稳定的问题。

Original summary in English

Summary by Sourcery

Bug Fixes:

• 通过支持使用 Range 请求恢复中断的下载，解决在下载大型备份文件时出现的不稳定和失败问题。

Original summary in English

Summary by Sourcery

Bug Fixes:

• Resolve instability and failures when downloading large backup files by allowing interrupted downloads to be resumed via Range requests.

[sourcery-ai]

Hey - 我已经审阅了你的更改，一切看起来都很棒！

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Original comment in English

Hey - I've reviewed your changes and they look great!

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