Continues Slice 0. Moves the near-pure modules, re-pointing the src-tauri
client/library types to the core crates (the make-or-break for a mechanical
extraction — verified the field shapes match):
- metadata: fetch_complete_metadata now takes &qbz_qobuz::QobuzClient (was
crate::api::QobuzClient); body compiles unchanged against qbz_models.
- migration: crate::api::QobuzClient -> qbz_qobuz::QobuzClient,
crate::library::database::LibraryDatabase -> qbz_library::LibraryDatabase,
super::metadata -> crate::metadata.
- playback: the PURE load_cmaf_bundle fn (the UI-events wrapper stays out —
it becomes a CacheEventSink call in the next commit).
Deps added: qbz-models, qbz-library, tokio, reqwest, lofty. Crate compiles.
purge + OfflineCacheState + downloader (CacheEvent) remain.
cc