perf(docker): use lightweight health probe

Avoid launching a full Node runtime every 30 seconds so idle containers do not create unnecessary CPU, memory, and disk pressure. Let Compose inherit the image probe to keep one source of truth.

Closes #1129

docker-compose.yml

@@ -49,18 +49,6 @@ services:
     security_opt:
       - no-new-privileges:true
     stop_grace_period: 30s
-    healthcheck:
-      test:
-        [
-          "CMD",
-          "node",
-          "-e",
-          "const p=process.env.PORT||3000;fetch('http://127.0.0.1:'+p+'/api/v1/health').then(r=>process.exit(r.ok?0:1)).catch(()=>process.exit(1))",
-        ]
-      interval: 30s
-      timeout: 5s
-      retries: 3
-      start_period: 20s
 
   postgres:
     container_name: bookorbit-db