Manual download cancellation uses the same internal error path as transfer
failures after the terminal-event ordering fix. That made the Tauri UI receive
DownloadGameFilesFailed and show a red failure state even though the user had
asked for the cancellation.
Keep a clone of the cancellation token in the download task and check it after
the transfer task returns an error. Cancelled downloads still refresh local
state and clear active operation tracking, but they no longer emit the failed
event. Real, uncancelled errors continue to send DownloadGameFilesFailed.
Add unit coverage for both branches so the UI-facing event contract stays
explicit.
Test Plan:
- just fmt
- just test
- just clippy
- git diff --check
Refs: manual cancel regression from app-state follow-up
ddidderr
a5307d3d6a
