i18n(core): route order-coordinator and token/margin guards through t()

These files bypassed the i18n table entirely, so a user running LANG=en still
got Chinese order logs. Migrating them surfaced structural duplication too: the
five order paths each spelled out their own 'quantity invalid' string, now one
key parameterised by an order-kind label.

Also fixes a type that carried display text as its domain: TrendLabel was
'做多' | '做空' | '无信号', so the engine's snapshot value *was* the Chinese
string and English rendering depended on matching it. Now 'long' | 'short' |
'none', translated at the edge.

Order-coordinator tests asserted the Chinese literals, which is exactly what
made the gap invisible; they now assert the resolved key so they hold in either
language.

39 new translation keys. 271 pass; tsc and oxlint clean.

tests/token-expiry-guard.test.ts

@@ -1,5 +1,6 @@
 import { describe, expect, it, vi, afterEach } from "vitest";
 import { standxTokenConfig } from "../src/config";
+import { t } from "../src/i18n";
 import { TokenExpiryGuard } from "../src/strategy/common/token-expiry-guard";
 
 const HOUR_MS = 3_600_000;
@@ -83,7 +84,7 @@ describe("TokenExpiryGuard", () => {
     await guard.evaluate({ positionAmt: 0, openOrderCount: 0 });
     await guard.evaluate({ positionAmt: 0, openOrderCount: 0 });
     const entryLogs = logs.filter(
-      ([type, detail]) => type === "info" && detail.includes("静默数据接收模式")
+      ([type, detail]) => type === "info" && detail === t("log.token.silentEntered")
     );
     expect(entryLogs).toHaveLength(1);
   });