feat: add selective file download for torrents

[iam-sahil]

When submitting this pull request, I confirm the following (please check the boxes):

• I have read and understood the Contributor Guidelines.
• I have checked that there are no duplicate pull requests related to this request.
• I have considered, and confirm that this submission is valuable to others.
• I accept that this submission may not be used and the pull request may be closed at the discretion of the maintainers.

Fill in PR content:

• Add torrent file selection UI with two-column modal layout
• Implement file priority setting in Python (libtorrent)
• Add /torrent-files endpoint to fetch file list from magnet links
• Calculate and display size of selected files accurately
• Support Windows file explorer-style filter buttons
• Add horizontal scrolling for long file names
• Position action buttons at bottom of modal
• Add caching for selected file size calculation
• Support both torrent file and magnet link metadata fetching

Known Issues:

• New file size for selected doesn't properly render in the downloads tab, it still shows the torrent size. It renders properly for some titles but fails for others. (Works for Silent Hill F)

Screenshots:

[iam-sahil]

Note: I have identified the cause of the wrongly displayed file sizes and I am working on a fix.

[iam-sahil]

@thegrannychaseroperation If you have any questions please hit me up, would love to see this merged.

I have fixed the file size calculation and caching issues as well.
No known errors yet.

[Wkeynhk]

Good job, I hope this pull request is accepted.

[sonarqubecloud]

Quality Gate passed

Issues
2 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud