Adiciona infra de deploy: Dockerfile multi-stage + nginx + .dockerignore

- Dockerfile: build com Node 20 (vite build) -> serve com nginx alpine
- nginx.conf: SPA routing, cache de assets versionados, healthcheck
- .dockerignore: exclui node_modules, dist e configs de IDE do contexto

nginx.conf

@@ -0,0 +1,30 @@
+server {
+    listen 80;
+    server_name _;
+
+    root /usr/share/nginx/html;
+    index index.html;
+
+    # SPA routing — 404s caem no index.html (i18next/react-router lidam)
+    location / {
+        try_files $uri $uri/ /index.html;
+    }
+
+    # Cache agressivo para assets versionados (Vite gera hash no nome)
+    location ~* \.(js|css|png|jpg|jpeg|gif|ico|svg|woff|woff2|ttf|eot|webp|avif)$ {
+        expires 1y;
+        add_header Cache-Control "public, immutable";
+    }
+
+    # index.html nunca cacheia (pega versão nova após deploy)
+    location = /index.html {
+        add_header Cache-Control "no-store, no-cache, must-revalidate";
+    }
+
+    # Healthcheck
+    location = /healthz {
+        access_log off;
+        return 200 "ok\n";
+        add_header Content-Type text/plain;
+    }
+}