Signing in triggered two back-to-back profile rebinds; the second re-added
the same Jellyfin connection, which tore down the live client and aborted
the home screen's in-flight fetches. The aborted pass was committed as
loaded-empty, flashing 'no content available' until the follow-up load
landed. Fix at the root instead of patching the sign-in window:
- addJellyfinConnection now reuses the live client when the connection is
unchanged (token, deviceId, URL set), matching the existing Plex
refreshTokensForProfile behavior; material changes still recreate it.
- Cancelled requests are classified end-to-end: the client's
treat-as-empty helpers rethrow cancellations, and the aggregation
fan-outs report cancelledServerIds alongside succeededServerIds.
- A fetch pass in which zero servers succeeded is never authoritative:
it keeps existing content instead of wiping it (also fixes the
pre-existing blanking of home/sidebar on a totally failed refresh),
stays in loading while disrupted (cancellation or binding in flight),
and only commits loaded-empty on a settled failure.
edde746