Pass PayPal client ID as build arg for client-side bundle

NEXT_PUBLIC_* vars must be available at build time to be inlined
into the client JS bundle. Added NEXT_PUBLIC_PAYPAL_CLIENT_ID as
a Docker build arg so the PayPal checkout button works in the browser.

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

frontend/Dockerfile

@@ -12,10 +12,12 @@ COPY . .
 
 # Build args
 ARG DIRECTUS_API_TOKEN
+ARG NEXT_PUBLIC_PAYPAL_CLIENT_ID
 
 # Set environment for build
 ENV NEXT_PUBLIC_DIRECTUS_URL=https://katheryn-cms.jeffemmett.com
 ENV DIRECTUS_API_TOKEN=${DIRECTUS_API_TOKEN}
+ENV NEXT_PUBLIC_PAYPAL_CLIENT_ID=${NEXT_PUBLIC_PAYPAL_CLIENT_ID}
 ENV NEXT_TELEMETRY_DISABLED=1
 
 # Build the application

frontend/docker-compose.yml

@@ -5,6 +5,7 @@ services:
       dockerfile: Dockerfile
       args:
         - DIRECTUS_API_TOKEN=katheryn-frontend-readonly-8591de0316ded82fab45328cf1e49cb1
+        - NEXT_PUBLIC_PAYPAL_CLIENT_ID=${NEXT_PUBLIC_PAYPAL_CLIENT_ID}
     container_name: katheryn-frontend
     restart: unless-stopped
     env_file: