fix: healthcheck — replace GNU-wget -I flag with --spider

BusyBox wget in alpine doesn't support -I flag, healthcheck was
failing with 'unrecognized option' and Docker reported container
as unhealthy despite nginx working correctly.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

docker-compose.yml

@@ -9,7 +9,7 @@ services:
     ports:
       - "127.0.0.1:4083:8080"
     healthcheck:
-      test: ["CMD", "wget", "-qO-", "-I", "http://127.0.0.1:8080/"]
+      test: ["CMD", "wget", "-q", "--spider", "http://127.0.0.1:8080/"]
       interval: 30s
       timeout: 5s
       retries: 3