stacks: add Kokoro, VibeVoice 1.5B, Chatterbox Turbo (TTS slate fill-in)

Three TTS additions to round out coverage on irv-ml1, each filling a
distinct niche the existing slate doesn't own.

Final coverage matrix (all on irv-ml1):
  Kokoro              — low-latency English, fixed voice library, ~300ms TTFA
  Chatterbox Turbo    — low-latency English w/ voice cloning + paralinguistic tags
  IndexTTS-2          — English voice cloning + emotion vector / text control
  Qwen3-TTS-1.7B-Base — high-quality English voice cloning
  CosyVoice 3         — multilingual (Chinese-leaning)
  VibeVoice 1.5B      — long-form / multi-speaker dialogue

stacks/kokoro:
  - port 8193, GPU device 0 (3090)
  - pulls ghcr.io/remsky/kokoro-fastapi-gpu:v0.2.4-master (no Dockerfile,
    no first-run model download — models baked in)
  - 60+ built-in voices, OpenAI-compat with stream=true over chunked HTTP
  - Apache-2.0 weights + code, ~1 GB VRAM

stacks/vibevoice:
  - port 8194, GPU device 1 (A6000 — for 7B headroom)
  - builds groxaxo/VibeVoice-FastAPI1 (more current fork of ncoder-ai)
    pinned to 7614c469a145
  - default model microsoft/VibeVoice-1.5B (~7 GB bf16 VRAM); env var
    swap to rsxdalv/VibeVoice-Large (7B) or FabioSarracino/VibeVoice-Large-Q8
  - multi-speaker dialogue via /v1/vibevoice/generate with Speaker N: format
  - long-form niche only — not low-latency

stacks/chatterbox:
  - port 8196, GPU device 0 (3090)
  - builds devnen/Chatterbox-TTS-Server (most active Turbo-supporting wrapper)
  - default model ResembleAI/chatterbox-turbo (~2.5 GB fp16, ~75ms latency)
  - paralinguistic tags inline ([laugh] [whisper] etc) — different shape
    from IndexTTS-2's emotion vector; fills the speed+cloning niche
    Kokoro/IndexTTS don't cover together
  - mandatory PerTh watermark on outputs (Resemble policy)

Three matching playbooks under playbooks/deploy-{kokoro,vibevoice,
chatterbox}.yaml. All idempotent, creates-/when-gated.

Cold-deploy disk on /worktank/: ~7 GB Kokoro + ~19 GB VibeVoice 1.5B
+ ~12 GB Chatterbox = ~38 GB total. VRAM concurrent: ~10-11 GB across
both GPUs.

Skipped from the original four-stack proposal: VibeVoice Realtime
(overlaps Kokoro's niche; Kokoro wins on latency, license, and not
needing a build).

stacks/chatterbox/.env.example

@@ -0,0 +1,52 @@
+# Chatterbox Turbo stack tunables. Copy to `.env` on irv-ml1 before
+# deploying.
+
+# ── build pin ────────────────────────────────────────────────────────
+# SHA of devnen/Chatterbox-TTS-Server. Bump + rebuild when you want
+# upstream wrapper updates. Pin a SHA — the wrapper has no tagged
+# releases yet.
+CHATTERBOX_SHA=main
+
+# Local image tag — bump when you change build context to force a
+# fresh layer build.
+CHATTERBOX_TAG=v1
+
+# ── network ──────────────────────────────────────────────────────────
+# Host port. Container listens on 8004 internally.
+# Reserved on irv-ml1: 8188 ComfyUI, 8190 CosyVoice, 8191 Qwen3-TTS,
+# 8192 IndexTTS-2, 8193 Kokoro, 8194 VibeVoice, 8765 Parakeet.
+# 8196 picked here.
+CHATTERBOX_PORT=8196
+
+# Bind address. 0.0.0.0 exposes on all interfaces (incl. WG tunnel
+# interface 10.100.79.3); 127.0.0.1 restricts to local-only.
+CHATTERBOX_BIND=0.0.0.0
+
+# ── runtime / GPU ────────────────────────────────────────────────────
+# Devices visible inside the container. "0" pins to the RTX 3090.
+# Chatterbox Turbo is small (~2.5 GB fp16) — the 3090 is plenty.
+CHATTERBOX_GPU_DEVICES=0
+
+# Model checkpoint. Options:
+#   ResembleAI/chatterbox-turbo         — flagship Turbo, 350M, EN-only,
+#                                         ~2.5 GB fp16, ~75 ms latency
+#   ResembleAI/chatterbox               — base Chatterbox, 500M, EN-only,
+#                                         ~3.5 GB fp16, slower but with
+#                                         exaggeration/CFG-weight knobs
+#   ResembleAI/chatterbox-multilingual  — 23 languages, slower than Turbo
+CHATTERBOX_MODEL_REPO=ResembleAI/chatterbox-turbo
+
+# ── persistent storage on the host ───────────────────────────────────
+# Reference audio dir for voice cloning. Drop short (~5 s) reference
+# WAVs in here; the wrapper picks them up by filename. Cloned voices
+# need the original reference to recreate — included in restic.
+CHATTERBOX_REFERENCE_DIR=/worktank/chatterbox/reference_audio
+
+# HuggingFace cache — Chatterbox Turbo weights (~6 GB) land here on
+# first start. Bind-mounted so they survive container recreate.
+# Excluded from restic (regenerable from HF).
+CHATTERBOX_CACHE_DIR=/worktank/chatterbox/cache
+
+# Optional: mount a host config.yaml for hot-edit. Leave commented
+# out in compose.yaml unless you actively want this.
+# CHATTERBOX_CONFIG=/worktank/chatterbox/config.yaml