Add currency settings, Settings service, and dialog to select fiat currency. Add support for non Official currencies like DOGE when using rates.

tests/cli/rates-format.test.ts

@@ -0,0 +1,40 @@
+/// <reference types="node" />
+
+import { describe, expect, test } from "vitest";
+
+import { BaseRates } from "../../src/utils/rates/base-rates";
+
+/**
+ * Minimal concrete adapter used only for testing BaseRates helpers.
+ */
+class TestRatesAdapter extends BaseRates {
+  public async start(): Promise<void> {
+    return;
+  }
+
+  public async stop(): Promise<void> {
+    return;
+  }
+
+  public async listPairs(): Promise<Set<string>> {
+    return new Set(["USD/BCH", "DOGE/BCH"]);
+  }
+}
+
+describe("BaseRates.formatCurrency", () => {
+  test("formats ISO currency codes with Intl currency style", () => {
+    const rates = new TestRatesAdapter();
+    const formatted = rates.formatCurrency(12.5, "USD");
+
+    expect(formatted).toContain("$");
+    expect(formatted).toContain("12.50");
+  });
+
+  test("formats non-ISO symbols without throwing", () => {
+    const rates = new TestRatesAdapter();
+    const formatted = rates.formatCurrency(12.3456789, "DOGE");
+
+    expect(formatted).toContain("DOGE");
+    expect(formatted).toContain("12.3456789");
+  });
+});