fix: set ARG before COPY for VITE_API_BASE to work in build

Dockerfile

@@ -3,11 +3,14 @@ FROM node:20-alpine AS build
 WORKDIR /app
 COPY package.json package-lock.json* ./
 RUN npm install
-COPY . .
+
+# Set build args and env vars BEFORE copying source code
 ARG VITE_WIZARD_PORT=18080
 ARG VITE_API_BASE
 ENV VITE_WIZARD_PORT=$VITE_WIZARD_PORT
 ENV VITE_API_BASE=$VITE_API_BASE
+
+COPY . .
 RUN npm run build
 
 # Production stage — lightweight static server, no nginx