Restructure Dockerfile based on pnpm docs

Dockerfile

@@ -1,46 +1,44 @@
-# Stage 1: Builder
-FROM node:20-alpine AS builder
-
-# Install system dependencies for image manipulation (ImageMagick v7+)
-RUN apk add --no-cache imagemagick libwebp libwebp-tools ghostscript
-
-# Enable pnpm
-RUN corepack enable
-
-# WORKDIR /app
-
-# Copy dependency files and install dependencies
-# This is cached separately from the source code
+# Stage 1: Dependency Fetching
+FROM node:20-alpine AS deps
+WORKDIR /app
+RUN npm i -g pnpm
 COPY package.json pnpm-lock.yaml ./
-RUN pnpm install --frozen-lockfile
+RUN pnpm fetch
 
-# Copy the rest of the application source code
+# Stage 2: Builder
+FROM node:20-alpine AS builder
+WORKDIR /app
+RUN npm i -g pnpm
+
+# Install system dependencies
+RUN apk add --no-cache imagemagick ghostscript
+
+# Copy the dependency manifests and then run install.
+COPY package.json pnpm-lock.yaml ./
+RUN pnpm install --frozen-lockfile --offline
+
+# Copy the rest
 COPY . .
 
 # --- Asset Generation Step ---
-RUN ls -la .
-RUN ls -la /scripts
 RUN chmod +x ./scripts/*.sh && ./scripts/first_page_image.sh
 
-# Run the build command
+# Run the build.
 RUN pnpm build
 
-# ---
-
-# Stage 2: Runner
+# Stage 3: Runner
 FROM node:20-alpine AS runner
-# WORKDIR /app
+WORKDIR /app
 
-# Create a non-root user for security
+# Create a non-root user for better security
 RUN addgroup --system --gid 1001 nodejs
 RUN adduser --system --uid 1001 nextjs
 USER nextjs
 
-# Copy the standalone output from the builder stage
-# The './public' directory now contains the newly generated assets
-COPY --from=builder /public ./public
-COPY --from=builder --chown=nextjs:nodejs .next/standalone ./
-COPY --from=builder --chown=nextjs:nodejs .next/static ./.next/static
+# Copy only the necessary production artifacts from the builder stage
+COPY --from=builder /app/public ./public
+COPY --from=builder --chown=nextjs:nodejs /app/.next/standalone ./
+COPY --from=builder --chown=nextjs:nodejs /app/.next/static ./.next/static
 
 EXPOSE 3000
 ENV PORT=3000