The global handle in web_server.py was named soulseek_client for
historical reasons but the type has long been DownloadOrchestrator,
not SoulseekClient. Renamed the global plus every parameter/attribute
that carried the legacy name.
- web_server.py: global var renamed; all 99 references updated.
- api/, core/downloads/*, core/search/*, core/streaming/*,
services/sync_service.py: parameter names, dataclass fields, and
init() arg names renamed.
- Test fixtures (CandidatesDeps, MasterDeps, SearchDeps, etc.) and
the _build_deps helpers updated accordingly.
The core.soulseek_client module path and SoulseekClient class name
(the actual soulseek-only client) are unchanged — only the orchestrator
handle renamed. Module imports of TrackResult/AlbumResult/DownloadStatus
from core.soulseek_client preserved.