The merge commit took only the staged index; these reconciliation edits sat
unstaged in the working tree. Integrate the template mechanism with #79's
region write (hq 128): RosterFile gains Shared, FactsInto sets into:block for
a shared fact, /etc/hosts becomes the region form (no floor) and node-names is
marked shared. Without this the merge would have regressed /etc/hosts back to
a whole-file write, replacing the operator's own lines.