[BUG]: 对应目录下存在同名文件导致下载任务状态不明

Description

如果多次下载同一文件，或者对应目录下存在同名文件（或者文件HASH值一致），下载任务应该自动对当前下载文件名添加序号用于区分并存多个相同文件。

Motrix Next Version

Motrix Next v3.9.9-beta.3

Issue Source

Motrix Next App

Platform

Windows (x64)

OS Version

Windows 11 Pro 25H2 26200.9445

Steps to Reproduce

1.曾完成过同一文件的下载 2.创建重复下载任务 3.下载任务状态不明

Diagnostic Logs

motrix-next-logs-20260911.zip

Screenshots

Validations

• I have searched existing issues and tested with the latest beta release when possible.
• I have uploaded the exported diagnostic .zip directly, or kept the same ZIP structure after redaction.
• This is a reproducible Motrix Next desktop-app bug. Questions belong in GitHub Discussions, browser-extension-only issues belong in motrix-next-extension, and engine-only issues belong in aria2-next.