fix: revert to node:18 (cached), enable crypto via NODE_OPTIONS

Docker Hub is unreachable from server, so node:20 can't be pulled.
Reverting to node:18-alpine (already cached) and using
--experimental-global-webcrypto to enable globalThis.crypto.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Dockerfile.service

@@ -2,7 +2,7 @@
 # Usage: docker build --build-arg SERVICE_NAME=auth-service --build-arg SERVICE_PORT=3001 -f Dockerfile.service .
 
 # ===== Build Stage =====
-FROM node:20-alpine AS builder
+FROM node:18-alpine AS builder
 
 RUN corepack enable
 
@@ -37,7 +37,7 @@ ARG SERVICE_NAME
 RUN pnpm turbo build --filter='./packages/shared/*' --filter=@it0/${SERVICE_NAME}
 
 # ===== Production Stage =====
-FROM node:20-alpine
+FROM node:18-alpine
 
 RUN corepack enable
 
@@ -77,4 +77,5 @@ ARG SERVICE_PORT=3000
 EXPOSE ${SERVICE_PORT}
 
 ENV SERVICE_NAME=${SERVICE_NAME}
+ENV NODE_OPTIONS="--experimental-global-webcrypto"
 CMD node dist/services/${SERVICE_NAME}/src/main

it0-web-admin/Dockerfile

@@ -1,5 +1,5 @@
 # Next.js standalone production Dockerfile
-FROM node:20-alpine AS builder
+FROM node:18-alpine AS builder
 
 WORKDIR /app
 
@@ -11,7 +11,7 @@ COPY . .
 RUN npm run build
 
 # ===== Production =====
-FROM node:20-alpine
+FROM node:18-alpine
 
 WORKDIR /app