Add dol utility for dotfiles lifecycle management

[MatthewDolan]

Summary

• add new dol utility to manage install/check/update flows for dotfiles and agents
• keep legacy upgrade/check/install entrypoints as compatibility wrappers that forward to dol
• update shell startup to run a unified daily dol check, and document/test the new behavior

Testing

• . ./bin/activate-hermit && ./ci/test.sh