- let core.metadata.registry own per-profile Spotify client caching
- register the DB-backed profile credentials provider from web_server.py
- invalidate only the affected profile cache entry on save, delete, and auth
- make web_server.py read and refresh Spotify from core.metadata.registry
- add single-key metadata cache eviction for Spotify reauth
- export the new cache helper through the metadata package shims
- split metadata lookup logic into core/metadata/*
- keep core/metadata_service.py as the legacy barrel
- update tests and artist-detail code to patch concrete modules
- Keep existing metadata_cache and metadata_service at the top level for now
- Move the new branch-local metadata helpers under core/metadata
- Share MusicBrainz release cache state from core.metadata.source and update import sites
