chore(homelab): add LibreTranslate service to runner compose

- libretranslate/libretranslate:latest, internal Docker network only
- LT_LOAD_ONLY=en,ru,id,pt,fr (only pairs the runner needs)
- LT_API_KEYS=true, key stored in Doppler prd_homelab
- Runner depends_on libretranslate (service_healthy)
- LIBRETRANSLATE_URL=http://libretranslate:5000 (no tunnel needed)
- RUNNER_MAX_CONCURRENT_TRANSLATION wired from Doppler

homelab/runner/docker-compose.yml

@@ -12,6 +12,7 @@
 #   - VALKEY_ADDR             → unset (not exposed publicly)
 #   - RUNNER_SKIP_INITIAL_CATALOGUE_REFRESH=true
 #   - Redis service for Asynq task queue (local to homelab, exposed to prod via Caddy TCP proxy)
+#   - LibreTranslate service for machine translation (internal network only)
 
 services:
   redis:
@@ -29,6 +30,26 @@ services:
       timeout: 5s
       retries: 5
 
+  libretranslate:
+    image: libretranslate/libretranslate:latest
+    restart: unless-stopped
+    environment:
+      LT_API_KEYS: "true"
+      LT_API_KEYS_DB_PATH: "/app/db/api_keys.db"
+      # Limit to source→target pairs the runner actually uses
+      LT_LOAD_ONLY: "en,ru,id,pt,fr"
+      LT_DISABLE_WEB_UI: "true"
+      LT_UPDATE_MODELS: "false"
+    volumes:
+      - libretranslate_models:/home/libretranslate/.local/share/argos-translate
+      - libretranslate_db:/app/db
+    healthcheck:
+      test: ["CMD-SHELL", "curl -sf http://localhost:5000/languages || exit 1"]
+      interval: 30s
+      timeout: 10s
+      retries: 5
+      start_period: 120s
+
   runner:
     image: kalekber/libnovel-runner:latest
     restart: unless-stopped
@@ -36,6 +57,8 @@ services:
     depends_on:
       redis:
         condition: service_healthy
+      libretranslate:
+        condition: service_healthy
     environment:
       # ── PocketBase ──────────────────────────────────────────────────────────
       POCKETBASE_URL: "https://pb.libnovel.cc"
@@ -64,6 +87,10 @@ services:
       # ── Pocket TTS ──────────────────────────────────────────────────────────
       POCKET_TTS_URL: "${POCKET_TTS_URL}"
 
+      # ── LibreTranslate (internal Docker network) ────────────────────────────
+      LIBRETRANSLATE_URL: "http://libretranslate:5000"
+      LIBRETRANSLATE_API_KEY: "${LIBRETRANSLATE_API_KEY}"
+
       # ── Asynq / Redis (local service) ───────────────────────────────────────
       # The runner connects to the local Redis sidecar.
       REDIS_ADDR: "redis:6379"
@@ -74,6 +101,7 @@ services:
       RUNNER_POLL_INTERVAL: "${RUNNER_POLL_INTERVAL}"
       RUNNER_MAX_CONCURRENT_SCRAPE: "${RUNNER_MAX_CONCURRENT_SCRAPE}"
       RUNNER_MAX_CONCURRENT_AUDIO: "${RUNNER_MAX_CONCURRENT_AUDIO}"
+      RUNNER_MAX_CONCURRENT_TRANSLATION: "${RUNNER_MAX_CONCURRENT_TRANSLATION}"
       RUNNER_TIMEOUT: "${RUNNER_TIMEOUT}"
       RUNNER_METRICS_ADDR: "${RUNNER_METRICS_ADDR}"
       RUNNER_SKIP_INITIAL_CATALOGUE_REFRESH: "true"
@@ -90,3 +118,5 @@ services:
 
 volumes:
   redis_data:
+  libretranslate_models:
+  libretranslate_db: