update dockerfile

frontend/Dockerfile

@@ -1,15 +1,20 @@
-# frontend/Dockerfile
+# ==== frontend/Dockerfile (production) ====
+
+# ---------- Builder ----------
 FROM node:20-alpine AS builder
 
 WORKDIR /app
 COPY package*.json ./
-RUN npm ci          # clean install, respects lockfile
+RUN npm ci                     # clean install, respects lockfile
 
 COPY . .
-RUN npm run build   # produces ./dist
+RUN npm run build              # Vite outputs to ./dist
 
-# ---- Runtime image (optional) ----
-FROM nginx:stable-alpine
+# ---------- Runtime ----------
+FROM nginx:stable-alpine AS runtime
+
+# Copy the compiled assets from the builder stage
 COPY --from=builder /app/dist /usr/share/nginx/html
+
 EXPOSE 80
 CMD ["nginx", "-g", "daemon off;"]