fix: compose healthchecks use 127.0.0.1, not localhost

Inside the frontend and nginx containers, localhost resolves to ::1
only while their nginx binds IPv4 — the wget healthcheck was refused
and both containers reported unhealthy despite serving fine.

Generated with [Devin](https://devin.ai)

Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

docker-compose.dev.yml

@@ -6,7 +6,7 @@ services:
     ports:
       - "${MAILPIT_HTTP_PORT}:8025"
     healthcheck:
-      test: ["CMD-SHELL", "wget -qO- http://localhost:8025/ >/dev/null 2>&1 || exit 1"]
+      test: ["CMD-SHELL", "wget -qO- http://127.0.0.1:8025/ >/dev/null 2>&1 || exit 1"]
       interval: 15s
       timeout: 5s
       retries: 10