- 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
- pass the selected manual match through singles import
- keep the import context source-aware so artist and album stay correct
- avoid treating non-Spotify IDs as wishlist Spotify IDs
- make wishlist logging and local variable names source-neutral
- Move import flow modules into a dedicated package
- Update app and test imports to the new namespace
- Group the import-focused tests under tests/imports
