Changed from raw Darwin kernel info to user-friendly versions:
- os: 'macOS' instead of 'Darwin'
- os_version: '15.4' instead of full kernel string
- os_release: '24.4.0' (kernel version)

Example: macOS 15.4 (Sequoia) now shows as:
  os=macOS, os_version=15.4, os_release=24.4.0

This makes analytics more readable and meaningful.