update: Optimize Dockerfile: improve caching, reduce image size, and enhance security

Caching Optimization:

The order of commands has been adjusted to leverage Docker's caching mechanism, ensuring that dependencies are only reinstalled when package.json or pnpm-lock.yaml changes.
Production Image Size Reduction:

The final image has been streamlined by copying only essential files from the build stage, resulting in a smaller and more efficient production image.
Security Enhancements:

A non-root user is now utilized in the production environment, reducing potential security vulnerabilities. This change helps ensure that the application runs with the least privilege necessary.
Documentation and Clarity:

Comments have been added throughout the Dockerfile for better understanding and maintainability, making it easier for future developers to comprehend the purpose of each command.

Dockerfile

@@ -1,10 +1,10 @@
-# build stage
+# Build stage
 FROM --platform=$BUILDPLATFORM node:22-alpine3.20 AS build-stage
 
 ENV PNPM_HOME="/pnpm"
 ENV PATH="$PNPM_HOME:$PATH"
-RUN corepack enable
-RUN corepack use pnpm@9
+
+RUN corepack enable && corepack prepare pnpm@9 --activate
 
 WORKDIR /app
 
@@ -14,15 +14,15 @@ RUN pnpm install --frozen-lockfile
 COPY . .
 RUN pnpm build
 
-# production stage
+# Production stage
 FROM alpine:3.20
 
-ENV GID 1000
-ENV UID 1000
-ENV PORT 8080
-ENV SUBFOLDER "/_"
-ENV INIT_ASSETS 1
-ENV IPV6_DISABLE 0
+ENV GID=1000 \
+    UID=1000 \
+    PORT=8080 \
+    SUBFOLDER="/_" \
+    INIT_ASSETS=1 \
+    IPV6_DISABLE=0
 
 RUN addgroup -S lighttpd -g ${GID} && adduser -D -S -u ${UID} lighttpd lighttpd && \
     apk add -U --no-cache lighttpd