The open-scrobble sweep was queued in the deferred background-init list,
which runs concurrently with the HTTP listener; a resume immediately after
restart could start new scrobbles before the previous process's open
sessions were stopped, leaving overlapping/stale scrobbles on remote
providers. Run the sweep synchronously before the listener starts, bounded
by a 30s timeout so an unreachable provider can't hang startup (the heavier
non-critical init stays deferred).
Addresses PR #21 review (P2).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
