feat(ops): web + worker container healthchecks (#20)

docker-compose only health-checked db. Add:
- web: an unauthenticated GET /api/health (excluded from the auth middleware) +
  a compose healthcheck that hits it (node global fetch — no curl/wget in image).
- worker: a background daemon thread touches /tmp/worker.alive every ~15s
  (independent of the main loop, so it stays fresh through a long download) +
  a compose healthcheck on the file's mtime (unhealthy if >90s stale).

Now `docker compose ps` reports real health for all services.
worker 223 tests, web 154, tsc + build + compose config clean.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

docker-compose.yml

@@ -24,9 +24,19 @@ services:
       LYRA_SECRET_KEY: ${LYRA_SECRET_KEY}
       # Optional shared-password gate for the whole UI/API. Unset ⇒ app is open. See README.
       LYRA_PASSWORD: ${LYRA_PASSWORD:-}
+      # Next's standalone server binds to HOSTNAME; default is the container hostname (its own
+      # IP only), so loopback healthchecks can't reach it. Bind all interfaces instead.
+      HOSTNAME: 0.0.0.0
     ports:
       # host:container — host 8770 avoids the Quill app on 3000 (and Lidarr on 8686)
       - "8770:3000"
+    healthcheck:
+      # unauthenticated liveness endpoint; node 22 has global fetch (no curl/wget in the image)
+      test: ["CMD-SHELL", "node -e \"fetch('http://127.0.0.1:3000/api/health').then(r=>process.exit(r.ok?0:1)).catch(()=>process.exit(1))\""]
+      interval: 30s
+      timeout: 5s
+      retries: 3
+      start_period: 20s
     depends_on:
       db:
         condition: service_healthy
@@ -55,6 +65,14 @@ services:
       # empty local dir so the mount is always valid; Soulseek delivery only works once
       # this points at the real slskd downloads directory.
       - ${SLSKD_DOWNLOADS_DIR:-./slskd-downloads}:/slskd-downloads
+    healthcheck:
+      # the worker touches /tmp/worker.alive every ~15s from a background thread (survives long
+      # downloads); unhealthy if it hasn't been touched in 90s (process wedged/exited).
+      test: ["CMD-SHELL", "test $(( $(date +%s) - $(stat -c %Y /tmp/worker.alive 2>/dev/null || echo 0) )) -lt 90"]
+      interval: 30s
+      timeout: 5s
+      retries: 3
+      start_period: 20s
     depends_on:
       db:
         condition: service_healthy