stacks: add dia + zonos to the TTS bench

dia: Nari Labs dialogue TTS (Dia 1.6B / Dia2-1B / Dia2-2B) via
devnen/Dia-TTS-Server — OpenAI-compat, fills the multi-speaker
dialogue-scene slot for skaldsong. Port 8200 on irv-ml1.

zonos: Zyphra Zonos-v0.1 (Apache-2.0, 44kHz, emotion sliders) via the
official Gradio interface. Audition surface only — no OpenAI-compat
endpoint yet (needs the FastAPI fork to become skaldsong-pluggable).
Port 8199 on irv-ml1.

Both follow the chatterbox/fish-s2 convention: local image built from a
pinned wrapper SHA via buildx git-context, .env-driven port/GPU, python
healthcheck, homepage labels.

stacks/zonos/compose.yaml

@@ -0,0 +1,56 @@
+# Zonos-v0.1 (Zyphra's expressive multilingual open-weight TTS) served
+# via the OFFICIAL Zyphra/Zonos repo's Gradio interface.
+#
+# Why this stack exists alongside the other TTS:
+#   * Apache-2.0, 44 kHz output, zero-shot voice cloning from a
+#     10-30 s sample, and explicit emotion/conditioning sliders —
+#     a different control surface from tag-based engines.
+#   * Multilingual (EN/JA/ZH/FR/DE), trained on 200k+ hours.
+#   * Cheap to run (~6 GB VRAM, transformer variant ~3.6 GB weights).
+#
+# CAVEAT — this is an AUDITION/EVAL surface, not a skaldsong-pluggable
+# engine yet: the official repo ships a Gradio WebUI + Python SDK, NOT
+# an OpenAI-compatible /v1/audio/speech endpoint. To wire Zonos into
+# skaldsong's router we'd need the community FastAPI fork (Zyphra/Zonos
+# PR #73) or a thin adapter. Bench it by ear first; promote later if it
+# earns a slot.
+#
+# Image is built locally from the upstream repo's Dockerfile via docker
+# buildx git-context. All tunables live in .env — edit that, not this.
+
+services:
+  zonos:
+    image: local/zonos:${ZONOS_TAG}
+    build:
+      # Single Dockerfile at repo root; bundles espeak-ng (required for
+      # Zonos's eSpeak phonemization).
+      context: https://github.com/Zyphra/Zonos.git#${ZONOS_SHA}
+      dockerfile: Dockerfile
+    container_name: zonos
+    restart: unless-stopped
+    runtime: nvidia
+    ports:
+      - "${ZONOS_BIND:-0.0.0.0}:${ZONOS_PORT}:7860"
+    environment:
+      - NVIDIA_VISIBLE_DEVICES=${ZONOS_GPU_DEVICES:-0}
+      - NVIDIA_DRIVER_CAPABILITIES=compute,utility
+      # Make Gradio bind all interfaces inside the container so the host
+      # port-map reaches it (Gradio otherwise may bind 127.0.0.1 only).
+      - GRADIO_SERVER_NAME=0.0.0.0
+      - HF_HOME=/app/hf_cache
+    volumes:
+      - ${ZONOS_CACHE_DIR}:/app/hf_cache
+    healthcheck:
+      # No JSON status route on the Gradio app — just probe the root
+      # page for liveness. start_period covers the first-boot model pull.
+      test: ["CMD-SHELL", "python3 -c \"import urllib.request,sys; urllib.request.urlopen('http://127.0.0.1:7860/', timeout=5); sys.exit(0)\""]
+      interval: 30s
+      timeout: 10s
+      retries: 3
+      start_period: 600s
+    labels:
+      - homepage.group=AI Systems
+      - homepage.name=Zonos
+      - homepage.icon=mdi-waveform
+      - homepage.description=Expressive multilingual TTS + cloning, 44kHz (Gradio eval, irv-ml1)
+      - homepage.href=http://10.100.79.3:${ZONOS_PORT}