fix(discover): sub-genre filter sends raw ids to the server (Tauri parity)

/discover/index honors sub-genre ids server-side, so send the raw selection
(parent or sub-genre, exactly as toggled) instead of mapping to the top-level
ancestor and narrowing client-side by genre.path — the previous hybrid widened
sub-genre selections back to their parent and dropped albums tagged only at top
level. Removes the client-side narrowing and its now-dead helpers; keeps a
diagnostic log of the outgoing genre_ids.

cc

crates/qbz-models/src/types.rs

@@ -766,6 +766,10 @@ pub struct LabelGetListResponse {
 pub struct Genre {
     pub id: u64,
     pub name: String,
+    /// Full ancestor id chain (top-level first, self last) as sent by the
+    /// discover endpoints. Absent on older cached payloads → None.
+    #[serde(default)]
+    pub path: Option<Vec<u64>>,
 }
 
 /// Genre info with full details