Squashes feat/personal-config-dsh-home: personal config.yaml and .env move
from ~/.config/dsh to the Harness home (~/.dsh), plus the module-graph,
lockfile, and i18n pairing regeneration that followed.
Squashes feat/install-script, feat/install-default-master, and
install-skip-clone: DSH_REF defaults to master, and running the script from
inside an existing checkout reuses it and skips the clone.
Tianyi Cui