fix(test): update the ForcedTradeStrategy fixture to the current engine listener API

[mrmx]

The integration fixture no longer compiles against a current engine.

Two things changed in the engine's listener API:

• onChange used to receive a StateStoreSupport and required an initStore(store) call before the store field could be used. It now receives the resolved StateStore directly — the store is event data, handed in alongside the values it belongs to, so there is no init ritual and no store field to hold.
• The listener base class was renamed AbstractOnChangeListener → AbstractWindowListener, since it is window-specific and the old name collided with java.awt.event.WindowListener in auto-import-heavy editors.

-        public void onChange(StateStoreSupport store, double prev, double actual) {
-            initStore(store);
-            long count = this.store.inc("count");
+        public void onChange(StateStore store, double prev, double actual) {
+            long count = store.inc("count");

Fixture-only change; no library code touched.