[Feature Request] Automatically save downloads to category folders based on file type

Description

Gopeed 2.0 Beta has a much improved UI, but it currently lacks an easy way to automatically save downloaded files into different folders based on file type/category.

For daily use, this is very useful when Gopeed is used as the main browser download manager. For example:

• .exe, .msi → Downloads/Programs
• .mp3, .flac → Downloads/Music
• .pdf, .docx, .xlsx, .pptx → Downloads/Documents
• .mp4, .mkv, .avi → Downloads/Videos
• .jpg, .png, .webp → Downloads/Pictures
• Other files → default download folder

Expected behavior

It would be great to have a built-in category/rule setting where users can:

1. Create or edit download categories.
2. Assign file extensions to each category.
3. Set a destination folder for each category.
4. Let Gopeed automatically choose the corresponding folder when a download is created from the browser extension or manually added URL.

Ideally, users could still override the destination folder for an individual task.

Why this matters

Gopeed already works very well as an integrated HTTP/HTTPS + BitTorrent download manager. Automatic file-type-based folder classification would make it much more convenient as a full replacement for download managers such as FDM, especially for users who download many different types of files from the browser.

Environment

• Gopeed: 2.0.0-beta.2
• Platform: Windows

Thanks for the great project.