fix: equipment buttons uniform height, trustProxy for real client IP

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

backend/src/app.ts

@@ -48,6 +48,7 @@ export async function buildApp() {
       }),
     },
     bodyLimit: 20 * 1024 * 1024, // 20MB — for base64 photo uploads
+    trustProxy: true, // get real IP from X-Real-IP / X-Forwarded-For via nginx
   })
 
   // ── File uploads & static ─────────────────────────────────────────────────