test: add unit tests for ProsodyOptions (edge-tts) (#6849)

Adds a small, focused, additive unit-test file (test/prosody-options.test.ts).
No existing files are modified or removed. yarn test:ci passes locally.

Co-authored-by: ytj-zuel <15623621570>
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: Jeniter

test/prosody-options.test.ts

@@ -0,0 +1,27 @@
+import { ProsodyOptions } from "../app/utils/ms_edge_tts";
+
+describe("ProsodyOptions", () => {
+  test("has sensible SSML defaults", () => {
+    const options = new ProsodyOptions();
+    expect(options.pitch).toBe("+0Hz");
+    expect(options.rate).toBe(1.0);
+    expect(options.volume).toBe(100.0);
+  });
+
+  test("allows overriding pitch, rate and volume", () => {
+    const options = new ProsodyOptions();
+    options.pitch = "+2st";
+    options.rate = "+50%";
+    options.volume = 50;
+    expect(options.pitch).toBe("+2st");
+    expect(options.rate).toBe("+50%");
+    expect(options.volume).toBe(50);
+  });
+
+  test("keeps two instances independent", () => {
+    const a = new ProsodyOptions();
+    const b = new ProsodyOptions();
+    a.rate = 2.0;
+    expect(b.rate).toBe(1.0);
+  });
+});