Every module contributes variables and PATH entries as facts, and one holder of
node-environment places them (novox/hq ADR 0203, to-be 41 WP3). This is that holder: no
package, no process, no tools — the directories it owns under the home and two files the
controller fills, the POSIX file at the path the seat fixes (~/.config/mesh/environment.sh,
sourced by the login shell) and environment.d's 50-mesh.conf for the account's service
manager and graphical session.
