docs: 📘 improve docs readability and organization

[sheldonhull]

• Improve docs organization by splitting out content into subfiles in docs.
• Remove references to tasks by make that have been replaced by mage.
• Refresh mage task list.
• Remove confusing mage job:setup when mage job:init and mage job:redeploy do the exact same thing.
• Only install Trunk if on macOS/Linux and also check for it already being installed before attempting to reinstall.
• Remove aqua env variable set in .envrc since this disruptes developer preferences.