fix(fifa17): preserve owned-pack reveal state for GET /purchased

Closes the reveal contract gap: POST /purchased opens a pack and returns
metadata; the client then polls GET /purchased for the opened items. Store BUY
returns items inline, but owned reward-pack (e.g. pack 70) opens had no reveal
read path, so a real FIFA session would show nothing after opening.

Faithful to the Python oracle (fut_store.last_pack / purchased pile): the reveal
is the set of owned items currently in the FIFA "purchased" pile — durable,
idempotent on repeat GET, cleared per-item when a card is moved to the club, and
appended-to by each open. Not a replay cache; presentation state derived from
the durable pile store + Core inventory.

- pile_store.rs: `list_by_pile(pile) -> Vec<core_item_id>` (reveal membership).
- economy_store.rs: `PurchasedPileSink` trait + optional `StoreDeps.purchased`;
  handle_store_buy/handle_pack_open record each minted item into the "purchased"
  pile. `shape_purchased_reveal` (pure): filter Core inventory to the purchased
  pile, shape with the SAME `shape_club_response` /club uses. Grants nothing,
  consumes no entitlement, allocates no id, moves no coins.
- lib.rs: EconomyRoute::PackReveal + classify_economy (GET purchased);
  BridgedPurchasedSink (records via the runtime bridge from the sync dispatch
  thread); dispatch reads the pile async + Core inventory sync + pure-shapes.

Scoping: single fifa17 profile/club (like the Python oracle), so all sessions
share one purchased pile — DIFFERENT-BY-DESIGN vs a per-SID cache, matching the
oracle's single-profile model.

Tests: pile_store::list_by_pile_filters_and_reflects_moves; and the dispatch E2E
now opens pack 70 (entitlement seeded via the Core economy API) and asserts GET
/purchased reveals the opened items and is idempotent on repeat. host 71 lib +
2 integration + 24 host_test green; clippy -D warnings + fmt clean.

openfut-utas-host/src/pile_store.rs

@@ -130,6 +130,22 @@ impl PileStore {
             }
         }
     }
+
+    /// Every Core owned-instance id currently recorded in `pile`, oldest first.
+    /// Used to render the `GET /purchased` reveal (the FIFA "purchased" pile).
+    pub async fn list_by_pile(&self, pile: &str) -> Result<Vec<String>, PileError> {
+        let rows = sqlx::query(
+            "SELECT core_item_id FROM item_pile WHERE pile = ? ORDER BY updated_at ASC",
+        )
+        .bind(pile)
+        .fetch_all(&self.pool)
+        .await
+        .map_err(db)?;
+        Ok(rows
+            .iter()
+            .map(|r| r.get::<String, _>("core_item_id"))
+            .collect())
+    }
 }
 
 #[cfg(test)]
@@ -184,4 +200,22 @@ mod tests {
             Some("purchased")
         );
     }
+
+    #[tokio::test]
+    async fn list_by_pile_filters_and_reflects_moves() {
+        let db = TempDb::new();
+        let store = PileStore::open(db.path()).await.unwrap();
+        store.set("a", "purchased").await.unwrap();
+        store.set("b", "purchased").await.unwrap();
+        store.set("c", "club").await.unwrap();
+        let mut purchased = store.list_by_pile("purchased").await.unwrap();
+        purchased.sort();
+        assert_eq!(purchased, vec!["a".to_string(), "b".to_string()]);
+        // Moving a card out of the purchased pile drops it from the reveal set.
+        store.set("a", "club").await.unwrap();
+        assert_eq!(
+            store.list_by_pile("purchased").await.unwrap(),
+            vec!["b".to_string()]
+        );
+    }
 }