feat(audio): add downloadable extra Piper voices with accents

Adds Alma (sv), Alan, Northern English, Cori, Alba (British/Scottish)
and Joe, John, Norman (American) as optional voices downloaded one at
a time from Settings, with gender (measured pitch) and accent shown in
the voice lists. The standard install is unchanged.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/tts.test.js

@@ -7,6 +7,7 @@ import { tmpdir } from "node:os";
 
 const require = createRequire(import.meta.url);
 const { createTts, listVoices, pickVoice, resolvePiperBinary } = require("../server/tts.js");
+const { installVoices, installAll, VOICES } = require("../server/tts_install.js");
 
 // Stand-in for execFile: records each call and writes the requested output file, so the
 // module's queueing/caching can be tested without a real Piper install.
@@ -64,6 +65,43 @@ test("voices need a matching .onnx.json, carry catalog gender labels, and the ch
   } finally { env.cleanup(); }
 });
 
+test("status offers the catalog voices that aren't installed yet, with gender and accent", () => {
+  const env = setup();
+  try {
+    const status = createTts({ dataDir: env.root, projectDir: env.root, voiceDirs: [env.voices] }).status();
+    const offered = Object.fromEntries(status.downloadable.map((voice) => [voice.name, voice]));
+    assert.equal(offered["sv_SE-nst-medium"], undefined, "installed voices are not offered again");
+    assert.deepEqual(offered["sv_SE-alma-medium"], { name: "sv_SE-alma-medium", language: "sv", gender: "female", accent: "", label: "Alma" });
+    assert.equal(offered["en_GB-alan-medium"].accent, "gb");
+    assert.equal(offered["en_GB-alan-medium"].gender, "male");
+    assert.equal(status.voices.find((voice) => voice.name === "en_US-ryan-medium").accent, "us");
+  } finally { env.cleanup(); }
+});
+
+test("a standard install skips the extra voices; picking one downloads only that voice", async () => {
+  const env = setup();
+  const originalFetch = globalThis.fetch;
+  const urls = [];
+  globalThis.fetch = async (url) => { urls.push(String(url)); return new Response("model"); };
+  try {
+    const target = join(env.root, "fresh-voices");
+    await installVoices({ voicesDir: target, log: () => {} });
+    const standard = VOICES.filter((voice) => !voice.extra).map((voice) => voice.name);
+    assert.deepEqual(standard, ["sv_SE-nst-medium", "sv_SE-lisa-medium", "en_US-ryan-medium", "en_US-lessac-medium"]);
+    assert.equal(urls.length, standard.length * 2, "model + config per standard voice");
+    assert.ok(!urls.some((url) => url.includes("en_GB")), "no extra voice in a standard install");
+
+    urls.length = 0;
+    await installVoices({ voicesDir: target, log: () => {}, names: ["en_GB-alan-medium"] });
+    assert.deepEqual(urls.map((url) => url.split("/main/")[1]), ["en/en_GB/alan/medium/en_GB-alan-medium.onnx.json", "en/en_GB/alan/medium/en_GB-alan-medium.onnx"]);
+    assert.ok(readdirSync(target).includes("en_GB-alan-medium.onnx"));
+    await assert.rejects(installAll({ projectDir: env.root, hasBinary: true, voice: "made_up-voice" }), /Unknown voice/);
+  } finally {
+    globalThis.fetch = originalFetch;
+    env.cleanup();
+  }
+});
+
 test("the Piper copy installed into the project is preferred over one on PATH", () => {
   const env = setup();
   try {