Add missing environment variables to Dockerfile for Docker deployments

[BeamNawapat]

Changes

Add support for VAPID (Voluntary Application Server Identification) keys in Docker builds:

• Add NEXT_PUBLIC_VAPID_PUBLIC_KEY as optional build argument and environment variable
• Add VAPID_PRIVATE_KEY as optional build argument and environment variable
• Include VAPID variables in all Docker build stages (builder, builder-two, runner)

Problem Solved

Fixes "Please enable Google services for push messaging" error that occurs when:

• Web push notifications are enabled in the application
• VAPID keys are not available during the Docker build process
• process.env.NEXT_PUBLIC_VAPID_PUBLIC_KEY returns undefined, causing invalid applicationServerKey