fix: include seed track when using GoToRadio

[anspangilinan]

Summary

Fix track-seeded radio sessions so the selected seed track is included at the front of the generated radio list.

Problem

When triggering GoToRadio on a track, the generated radio session omitted the selected track itself. This differs from Spotify's official client behavior, where the seed track is included.

Reproduction

1. Highlight a track
2. Press g, then a
3. Select GoToRadio
4. Observe that the resulting radio session does not include the selected track

Fixes: #856