Download tracking records incomplete/failed downloads

[Cassutti]

Describe the bug
The application records downloads in the history as soon as the download button is clicked, even if the download subsequently fails or is interrupted by the user. This results in inaccurate download statistics and misleading history.

To Reproduce
Steps to reproduce the behavior:

1. Log in to LibraryDownloadarr
2. Click download on any media file
3. Immediately cancel the download in the browser or disconnect network
4. Check Admin Dashboard → Download History
5. The download is recorded as if it completed successfully

Expected behavior
Downloads should only be recorded in the history when they complete successfully. Failed or interrupted downloads should either:

• Not be recorded at all, OR
• Be recorded with a status indicator (e.g., "failed", "cancelled", "incomplete")

Current behavior
All downloads are logged immediately when the button is clicked, regardless of actual completion status.

Environment

• Deployment method: Docker Compose on TrueNAS
• Browser: Chrome 120
• OS: Windows 11

Suggested solution
Implement download completion tracking by:

1. Only recording to history after successful file transfer completion
2. Add a status field to distinguish between successful, failed, and cancelled downloads
3. Optionally add download size verification to confirm completion