Update Dockerfile to enable corepack and use specific pnpm version

Author: hironow

frontend/web/Dockerfile

@@ -16,7 +16,9 @@ FROM base AS builder
 WORKDIR /app
 COPY --from=deps /app/node_modules ./node_modules
 COPY . .
-RUN corepack enable pnpm && pnpm run build
+RUN corepack enable && \
+    corepack prepare [email protected] --activate && \
+    pnpm run build
 
 # Stage 3: Production server
 FROM base AS runner