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/package.json

@@ -14,6 +14,8 @@
     "start": "NODE_ENV=production node dist/server/index.js",
     "typecheck": "tsc -p tsconfig.server.typecheck.json --noEmit",
     "generate:config-schema": "tsx scripts/generate-config-schema.ts",
+    "speech:models": "tsx scripts/list-speech-models.ts",
+    "speech:download": "tsx scripts/download-speech-models.ts",
     "test": "vitest run",
     "test:watch": "vitest",
     "test:ui": "vitest --ui",
@@ -48,6 +50,10 @@
     "pino-pretty": "^13.1.3",
     "playwright": "^1.56.1",
     "qrcode": "^1.5.4",
+    "@sctg/sentencepiece-js": "^1.1.0",
+    "onnxruntime-node": "^1.23.0",
+    "sherpa-onnx": "^1.12.23",
+    "sherpa-onnx-node": "^1.12.23",
     "strip-ansi": "^7.1.2",
     "tiny-invariant": "^1.3.3",
     "uuid": "^9.0.1",