fix: Docker healthcheck IPv6 connection refused

Changed healthcheck from localhost to 127.0.0.1 to force IPv4 connection.
The issue occurred because 'localhost' resolves to IPv6 (::1) but nginx
only listens on IPv4 by default, causing healthchecks to fail.

Error before fix:
  Connecting to localhost ([::1]:80)
  wget: can't connect to remote host: Connection refused

Updated both Dockerfile and docker-compose.yml for consistency.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

Dockerfile

@@ -48,9 +48,9 @@ RUN chown -R nginx:nginx /usr/share/nginx/html && \
 # Expose port 80
 EXPOSE 80
 
-# Health check
+# Health check (use 127.0.0.1 to force IPv4)
 HEALTHCHECK --interval=30s --timeout=10s --start-period=5s --retries=3 \
-  CMD wget --no-verbose --tries=1 --spider http://localhost/ || exit 1
+  CMD wget --no-verbose --tries=1 --spider http://127.0.0.1/ || exit 1
 
 # Run nginx
 CMD ["nginx", "-g", "daemon off;"]