fix for docker file error in pipeline

Author: NirajC-Microsoft

src/frontend/Dockerfile

@@ -1,23 +1,19 @@
 # Multi-stage Dockerfile for React frontend with Python backend support using UV
 
 # Stage 1: Node build environment for React
-FROM node:18-alpine AS frontend-builder
+FROM node:20-alpine AS frontend-builder
 
 WORKDIR /app/frontend
 
 # Copy package files first for better caching
 COPY package*.json ./
 
-# Install dependencies
-RUN npm ci --silent
-
-# Copy source files
+# Copy all source files
 COPY . ./
 
-RUN rm -rf node_modules && npm ci && npm rebuild esbuild --force
-
-# Build the React app
-RUN npm run build
+# Install dependencies and build in a single layer to avoid BuildKit overlay issues
+RUN --mount=type=cache,target=/root/.npm \
+    npm ci && npm run build
 
 # Stage 2: Python build environment with UV
 FROM python:3.11-slim-bullseye AS python-builder