Make SITE_URL and AUTH_SECRET configurable via environment variables for any deployment

Dockerfile

@@ -14,13 +14,21 @@ COPY . .
 # Create data directory for SQLite database
 RUN mkdir -p /app/data
 
+# Accept build arguments
+ARG SITE_URL=https://nlcc.rydertech.us
+ARG AUTH_SECRET
+
+# Set environment variables for build
+ENV SITE_URL=$SITE_URL
+ENV AUTH_SECRET=$AUTH_SECRET
+
 # Build the application
 RUN npm run build
 
 # Expose port
 EXPOSE 3000
 
-# Set environment variables
+# Set runtime environment variables
 ENV NODE_ENV=production
 ENV NUXT_HOST=0.0.0.0
 ENV NUXT_PORT=3000