feat: enhance order handling in LighterGateway and introduce order identity normalization for improved precision and consistency

tests/lighter/order-identity.test.ts

@@ -0,0 +1,23 @@
+import { describe, expect, it } from "vitest";
+import { normalizeOrderIdentity, orderIdentityEquals } from "../../src/exchanges/lighter/order-identity";
+
+describe("order identity helpers", () => {
+  it("treats large numeric strings as distinct values", () => {
+    const first = "27584547724798440";
+    const second = "27584547724798442";
+    expect(orderIdentityEquals(first, second)).toBe(false);
+    expect(orderIdentityEquals(first, first)).toBe(true);
+  });
+
+  it("considers numeric inputs equal to their string counterparts", () => {
+    expect(orderIdentityEquals(123456789, "123456789")).toBe(true);
+  });
+
+  it("normalizes whitespace-only identifiers to null", () => {
+    expect(normalizeOrderIdentity("   ")).toBeNull();
+  });
+
+  it("falls back to truncated integers for floating inputs", () => {
+    expect(normalizeOrderIdentity(42.9)).toBe("42");
+  });
+});