feat(#399): add Docker Compose dev overlay for speech services

Add docker-compose.speech.yml with three speech services:
- Speaches (STT via Whisper + basic TTS) on port 8090
- Kokoro-FastAPI (default TTS) on port 8880
- Chatterbox TTS (premium, GPU-required) on port 8881 behind
  the premium-tts profile

All services include health checks, connect to the mosaic-internal
network, and follow existing naming/labeling conventions. Makefile
targets added: speech-up, speech-down, speech-logs.

Fixes #399

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

docker-compose.speech.yml

@@ -0,0 +1,113 @@
+# ==============================================
+# Speech Services - Docker Compose Dev Overlay
+# ==============================================
+#
+# Adds STT and TTS services for local development.
+#
+# Usage:
+#   Basic (STT + default TTS):
+#     docker compose -f docker-compose.yml -f docker-compose.speech.yml up -d
+#
+#   With premium TTS (requires GPU):
+#     docker compose -f docker-compose.yml -f docker-compose.speech.yml --profile premium-tts up -d
+#
+#   Or use Makefile targets:
+#     make speech-up              # Basic speech services
+#     make speech-down            # Stop speech services
+#     make speech-logs            # View speech service logs
+# ==============================================
+
+services:
+  # ======================
+  # Speaches (STT + basic TTS)
+  # ======================
+  speaches:
+    image: ghcr.io/speaches-ai/speaches:latest
+    container_name: mosaic-speaches
+    restart: unless-stopped
+    environment:
+      WHISPER__MODEL: ${SPEACHES_WHISPER_MODEL:-Systran/faster-whisper-large-v3-turbo}
+    ports:
+      - "${SPEACHES_PORT:-8090}:8000"
+    volumes:
+      - speaches_models:/root/.cache/huggingface
+    healthcheck:
+      test: ["CMD-SHELL", "curl -f http://localhost:8000/health || exit 1"]
+      interval: 30s
+      timeout: 10s
+      retries: 5
+      start_period: 120s
+    networks:
+      - mosaic-internal
+    labels:
+      - "com.mosaic.service=speech-stt"
+      - "com.mosaic.description=Speaches STT (Whisper) and basic TTS"
+
+  # ======================
+  # Kokoro TTS (Default TTS)
+  # ======================
+  kokoro-tts:
+    image: ghcr.io/remsky/kokoro-fastapi:latest-cpu
+    container_name: mosaic-kokoro-tts
+    restart: unless-stopped
+    ports:
+      - "${KOKORO_TTS_PORT:-8880}:8880"
+    healthcheck:
+      test: ["CMD-SHELL", "curl -f http://localhost:8880/health || exit 1"]
+      interval: 30s
+      timeout: 10s
+      retries: 5
+      start_period: 120s
+    networks:
+      - mosaic-internal
+    labels:
+      - "com.mosaic.service=speech-tts"
+      - "com.mosaic.description=Kokoro FastAPI TTS engine"
+
+  # ======================
+  # Chatterbox TTS (Premium TTS - Optional)
+  # ======================
+  # Only starts with: --profile premium-tts
+  # Requires NVIDIA GPU with docker nvidia runtime
+  chatterbox-tts:
+    image: devnen/chatterbox-tts-server:latest
+    container_name: mosaic-chatterbox-tts
+    restart: unless-stopped
+    ports:
+      - "${CHATTERBOX_TTS_PORT:-8881}:8000"
+    profiles:
+      - premium-tts
+    deploy:
+      resources:
+        reservations:
+          devices:
+            - driver: nvidia
+              count: 1
+              capabilities: [gpu]
+    healthcheck:
+      test: ["CMD-SHELL", "curl -f http://localhost:8000/health || exit 1"]
+      interval: 30s
+      timeout: 10s
+      retries: 5
+      start_period: 180s
+    networks:
+      - mosaic-internal
+    labels:
+      - "com.mosaic.service=speech-tts-premium"
+      - "com.mosaic.description=Chatterbox premium TTS with voice cloning (GPU)"
+
+# ======================
+# Volumes
+# ======================
+volumes:
+  speaches_models:
+    name: mosaic-speaches-models
+    driver: local
+
+# ======================
+# Networks
+# ======================
+networks:
+  mosaic-internal:
+    external: true
+    name: mosaic-internal