- account settings: sidebar sections (profile, devices, security,
invitations, sync and sign-in) instead of one long scroll; inline device
rename, confirmations for destructive actions and toast feedback
- sign-in/register: split layout with a quiet brand column, text tabs and
underlined inputs; registering asks for the password twice and explains
that it cannot be recovered
- move invitation accept/label helpers into store/invitations so the
toast and the settings inbox share them
- add the home page zone styles used by the next commit
justme