feat(fifa17): add authoritative economy engine + fut_profile importer

Adds openfut-adapter-fifa17 fut::economy — the single-writer FIFA 17 economy engine
the eventual cluster cutover needs: coins + unopened-pack entitlements + owned
inventory + stable item ids, with all-or-nothing transactional mutations faithfully
ported from the Python oracle's fut_store.Store primitives.

Atomic ops: debit (fail-closed), credit, grant_pack/consume_pack (consume-once),
allocate_item_id (unique/monotonic), add_item, and composed transactions buy_pack,
open_pack, quick_sell, market_buy_now, grant_reward. Fail-closed everywhere; the
65534 sentinel can never be bought/granted/opened (defense at the grant primitive,
mirroring grant_unopened_pack rejecting non-catalogue ids). from_fut_profile importer
round-trips coins/unopenedPackIds/items/nextItemId and floors nextItemId past the
highest existing id so re-import cannot mint a duplicate. 10 unit tests (atomicity,
sentinel safety, consume-once, quick-sell, item-id uniqueness, import round-trip).

NOT wired (R3): the live coin balance is one indivisible writer set spanning Store
BUY, pack-open, quick-sell, match rewards AND the transfer market, all in
fut_profile.json; and the generic home (OpenFUT Core) is a preserved-dirty/frozen
submodule. So a safe single-writer cutover cannot be wired yet — this engine +
importer is the coherent prerequisite. No dual-write introduced. No deployment.

openfut-adapter-fifa17/src/fut/mod.rs

@@ -6,6 +6,7 @@
 //! socket — a Rust UTAS host wires it to Core later.
 pub mod catalog;
 pub mod club_response;
+pub mod economy;
 pub mod entities;
 pub mod item;
 pub mod owned_query;