Local streaming STT/TTS with Parakeet + Pocket TTS

- Add provider-agnostic streaming speech interfaces
- Local STT via Sherpa (Zipformer/Paraformer) + Parakeet v3 (offline)
- Local TTS via Pocket TTS ONNX (onnxruntime-node) with chunked streaming
- Auto-download models into PASEO_HOME and add Node download script
- Add E2E download test that round-trips TTS->STT

packages/server/scripts/download-speech-models.ts

@@ -0,0 +1,42 @@
+import { resolvePaseoHome } from "../src/server/paseo-home.js";
+import { createRootLogger } from "../src/server/logger.js";
+import { ensureSherpaOnnxModels } from "../src/server/speech/sherpa/model-downloader.js";
+import type { SherpaOnnxModelId } from "../src/server/speech/sherpa/model-catalog.js";
+
+function parseArgs(argv: string[]): { modelsDir: string; modelIds: SherpaOnnxModelId[] } {
+  const home = resolvePaseoHome();
+  let modelsDir = process.env.PASEO_SHERPA_ONNX_MODELS_DIR || `${home}/models/sherpa-onnx`;
+  const modelIds: SherpaOnnxModelId[] = [];
+
+  for (let i = 0; i < argv.length; i++) {
+    const arg = argv[i];
+    if (arg === "--models-dir") {
+      modelsDir = argv[i + 1] ?? modelsDir;
+      i++;
+      continue;
+    }
+    if (arg === "--model") {
+      const id = argv[i + 1] as SherpaOnnxModelId | undefined;
+      if (!id) {
+        throw new Error("--model requires a value");
+      }
+      modelIds.push(id);
+      i++;
+      continue;
+    }
+  }
+
+  if (modelIds.length === 0) {
+    const stt = (process.env.PASEO_SHERPA_STT_PRESET || "zipformer-bilingual-zh-en-2023-02-20") as SherpaOnnxModelId;
+    const tts = (process.env.PASEO_SHERPA_TTS_PRESET || "pocket-tts-onnx-int8") as SherpaOnnxModelId;
+    modelIds.push(stt, tts);
+  }
+
+  return { modelsDir, modelIds };
+}
+
+const logger = createRootLogger({ level: "info", format: "pretty" });
+
+const { modelsDir, modelIds } = parseArgs(process.argv.slice(2));
+await ensureSherpaOnnxModels({ modelsDir, modelIds, autoDownload: true, logger });
+logger.info({ modelsDir, modelIds }, "Done downloading speech models");

packages/server/scripts/list-speech-models.ts

@@ -0,0 +1,11 @@
+import { listSherpaOnnxModels } from "../src/server/speech/sherpa/model-catalog.js";
+
+const models = listSherpaOnnxModels()
+  .slice()
+  .sort((a, b) => a.kind.localeCompare(b.kind) || a.id.localeCompare(b.id));
+
+for (const m of models) {
+  // eslint-disable-next-line no-console
+  console.log(`${m.kind}\t${m.id}\t${m.description}`);
+}
+