chore: add Docker config for Dokploy deploy

Dockerfile

@@ -0,0 +1,21 @@
+# Stage 1: build
+FROM node:20-alpine AS builder
+WORKDIR /app
+COPY package*.json ./
+RUN npm ci
+COPY . .
+
+# Variables de entorno inyectadas como build args desde Dokploy
+ARG VITE_SUPABASE_URL
+ARG VITE_SUPABASE_ANON_KEY
+ENV VITE_SUPABASE_URL=$VITE_SUPABASE_URL
+ENV VITE_SUPABASE_ANON_KEY=$VITE_SUPABASE_ANON_KEY
+
+RUN npm run build
+
+# Stage 2: serve
+FROM nginx:alpine
+COPY --from=builder /app/dist /usr/share/nginx/html
+COPY nginx.conf /etc/nginx/conf.d/default.conf
+EXPOSE 80
+CMD ["nginx", "-g", "daemon off;"]