v0.1.3

Doctor and update commands.

• local-image-gen doctor and local-image-gen update (--doctor remains an alias)
• Doctor reports install freshness against official GitHub raw; generate jobs do not check GitHub
• Update is git pull --ff-only plus install.sh
• Dirty trees, unreadable git status, and non-git installs refuse to mutate
• After a pull, to / install.version are read from the on-disk script

Already installed:

local-image-gen doctor
local-image-gen update