Update Dockerfile to set user context and improve dependency installation

- Changed user to root for installing pnpm globally, then switched back to node for application work.
- Updated WORKDIR to ensure proper directory context for the application build process.

Dockerfile

@@ -1,7 +1,9 @@
 # Stage 1: Build the frontend
 FROM cgr.dev/chainguard/node:latest-dev AS node-builder
-WORKDIR /app
+USER root
 RUN npm install -g pnpm
+USER node
+WORKDIR /app
 COPY --chown=node:node package.json pnpm-lock.yaml ./
 RUN pnpm install --frozen-lockfile
 COPY --chown=node:node . .