fix: make asynq consumer actually claim and heartbeat translation tasks

ClaimNextTranslationTask and HeartbeatTask were no-ops in the asynq
Consumer, so translation tasks created in PocketBase were never picked
up by the runner. Translation tasks live in PocketBase (not Redis),
so they must be claimed/heartbeated via the underlying pb consumer.
ReapStaleTasks is also delegated so stale translation tasks get reset.

Also removes the LibreTranslate healthcheck from homelab/runner
docker-compose.yml and relaxes depends_on to service_started — the
healthcheck was blocking runner startup until models loaded (~2 min)
and the models are already pre-downloaded in the volume.

homelab/runner/docker-compose.yml

@@ -28,20 +28,13 @@ services:
     volumes:
       - libretranslate_models:/home/libretranslate/.local/share/argos-translate
       - libretranslate_db:/app/db
-    healthcheck:
-      test: ["CMD", "python3", "-c", "import urllib.request,sys; urllib.request.urlopen('http://localhost:5000/languages'); sys.exit(0)"]
-      interval: 30s
-      timeout: 10s
-      retries: 5
-      start_period: 120s
 
   runner:
     image: kalekber/libnovel-runner:latest
     restart: unless-stopped
     stop_grace_period: 135s
     depends_on:
-      libretranslate:
-        condition: service_healthy
+      - libretranslate
     environment:
       # ── PocketBase ──────────────────────────────────────────────────────────
       POCKETBASE_URL: "https://pb.libnovel.cc"