refactor(ui): extract useStrategyEngine from 9 duplicated screens

Every screen repeated the same block: resolve the exchange, build an adapter,
construct an engine, hold it in a ref, subscribe, clone the snapshot into state,
stop on unmount, and stop again on Escape. Roughly 45 lines each, differing only
in which engine they built and which arrays they cloned.

Two of them also carried their own copy of an availability rule — MakerPointsApp
re-checked 'standx' and BasisApp re-checked isBasisSupportedExchangeId — a third
and fourth statement of what the registry now owns. The hook reads
strategyUnavailableReason instead, so a screen cannot drift from the menu.

Screens now declare a strategy id and, when they render engine-owned arrays
beyond tradeLog, a cloneSnapshot. Engine construction leaves the view layer
entirely.

234 pass; tsc and oxlint clean; menu renders unchanged. -338 lines.

src/ui/SwingApp.tsx

@@ -1,11 +1,9 @@
-import React, { useEffect, useMemo, useRef, useState } from "react";
-import { Box, Text, useInput } from "ink";
-import { swingConfig } from "../config";
-import { getExchangeDisplayName, resolveExchangeId } from "../exchanges/create-adapter";
-import { buildAdapterFromEnv } from "../exchanges/resolve-from-env";
-import { SwingEngine, type SwingEngineSnapshot } from "../strategy/swing-engine";
+import React from "react";
+import { Box, Text } from "ink";
+import type { SwingEngineSnapshot } from "../strategy/swing-engine";
 import { formatNumber } from "../utils/format";
 import { DataTable, type TableColumn } from "./components/DataTable";
+import { useStrategyEngine } from "./useStrategyEngine";
 import { t } from "../i18n";
 
 const READY_MESSAGE = t("swing.readyMessage");
@@ -14,45 +12,11 @@ interface SwingAppProps {
   onExit: () => void;
 }
 
-const inputSupported = Boolean(process.stdin && (process.stdin as any).isTTY);
-
 export function SwingApp({ onExit }: SwingAppProps) {
-  const [snapshot, setSnapshot] = useState<SwingEngineSnapshot | null>(null);
-  const [error, setError] = useState<Error | null>(null);
-  const engineRef = useRef<SwingEngine | null>(null);
-  const exchangeId = useMemo(() => resolveExchangeId(), []);
-  const exchangeName = useMemo(() => getExchangeDisplayName(exchangeId), [exchangeId]);
-
-  useInput(
-    (_input, key) => {
-      if (key.escape) {
-        engineRef.current?.stop();
-        onExit();
-      }
-    },
-    { isActive: inputSupported }
-  );
-
-  useEffect(() => {
-    try {
-      const adapter = buildAdapterFromEnv({ exchangeId, symbol: swingConfig.symbol });
-      const engine = new SwingEngine(swingConfig, adapter);
-      engineRef.current = engine;
-      setSnapshot(engine.getSnapshot());
-      const handler = (next: SwingEngineSnapshot) => {
-        setSnapshot({ ...next, tradeLog: [...next.tradeLog], openOrders: [...next.openOrders] });
-      };
-      engine.on("update", handler);
-      engine.start();
-      return () => {
-        engine.off("update", handler);
-        engine.stop();
-      };
-    } catch (err) {
-      console.error(err);
-      setError(err instanceof Error ? err : new Error(String(err)));
-    }
-  }, [exchangeId]);
+  const { snapshot, error, exchangeName } = useStrategyEngine<SwingEngineSnapshot>("swing", {
+    onExit,
+    cloneSnapshot: (next) => ({ ...next, tradeLog: [...next.tradeLog], openOrders: [...next.openOrders] }),
+  });
 
   if (error) {
     return (