Clevertuna docs

Everything the README deliberately does not say. The same files live in docs/ in the repository.

• InstallmacOS, Linux, udev rules, Windows.
• UsageEvery command, window and flag.
• ThemesThe fifteen, the randomiser, the scheme file.
• SafetyWhat “verified” means, and the exit codes.
• ProtocolThe wire format, reverse-engineered.
• Hardware logWhat has actually been run against a keyboard.