feat(economy): purchase_items primitive + entitlement import seeding

purchase_items: generic atomic debit + mint of several items (fail-closed) for
open-on-buy Store packs (Store BUY returns items immediately) + POST
/economy/purchase-items route. Import: add optional entitlements[] to
ProfileImportRequest, seeding unconsumed packs rows in the same transaction (so a
source's unopened packs become Core entitlements); idempotency via the existing
import fingerprint. Tests: 2 purchase_items unit + endpoint + entitlement-seed
import. Core matrix 45 lib + 116 integration + 9 import green; clippy clean.

tests/integration_test.rs

@@ -2776,3 +2776,25 @@ async fn test_economy_insufficient_funds_fail_closed() {
         .iter()
         .any(|e| e["definition_id"] == "pack-x"));
 }
+
+#[tokio::test]
+async fn test_economy_purchase_items_debits_and_mints_all() {
+    let app = build_test_app().await;
+    auth(&app, "econ-e").await;
+    let (st, buy) = json_post(
+        &app,
+        "/economy/purchase-items",
+        serde_json::json!({
+            "cost": 800,
+            "items": [
+                {"item_id": "bx-1", "card_id": "d-1"},
+                {"item_id": "bx-2", "card_id": "d-2"}
+            ]
+        }),
+    )
+    .await;
+    assert_eq!(st, StatusCode::OK);
+    assert_eq!(buy["balance"], 4200);
+    let (_, bal) = json_get(&app, "/economy/balance").await;
+    assert_eq!(bal["balance"], 4200);
+}