build(deps): bump lofty to 0.24

Every 0.23.x release of lofty is yanked on crates.io, so the version
requirement only resolves from the committed Cargo.lock. A fresh resolve
of qbz-library or qbz-offline-cache as a dependency fails outright.

0.24.0 needs no code changes across the 19 call sites.

crates/qbz-offline-cache/Cargo.toml

@@ -22,7 +22,7 @@ reqwest = { workspace = true }
 futures-util = { workspace = true }
 
 # FLAC tag + artwork embedding (legacy-format post-processing)
-lofty = "0.23"
+lofty = "0.24"
 
 # Platform cache dir (default offline-root location)
 dirs = "6"