Fix docs healthcheck: use 127.0.0.1 instead of localhost

Nginx inside the docs container listens on IPv4 (0.0.0.0:80) but
wget resolves localhost to IPv6 (::1), causing connection refused.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

docker-compose.yml

@@ -1525,7 +1525,7 @@ services:
       - breakpilot-pwa-network
     restart: unless-stopped
     healthcheck:
-      test: ["CMD", "wget", "-q", "--spider", "http://localhost:80/"]
+      test: ["CMD", "wget", "-q", "--spider", "http://127.0.0.1:80/"]
       interval: 30s
       timeout: 10s
       retries: 3