fix: bring the docs in line with the no-admin route (release review)

Name the real trigger and CODEMAN_NO_ADMIN=0 in the READMEs and the
Installation page, add the install without git to the update tables and the
updater notes, record the installer's downloads in the supply chain section,
and say that the data directory question also removes a kept runtime.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/wiki/Settings-Reference.md

@@ -38,8 +38,8 @@ as usual and tells them that server-wide settings can only be changed by an admi
 ### Updates
 
 Current version, a manual check, and the in-app updater. Covers git-clone installs
-supervised by systemd or launchd; npm installs report as non-updatable. See
-[Running As A Service](Running-As-A-Service).
+supervised by systemd or launchd; npm installs and installs without git report as
+non-updatable. See [Running As A Service](Running-As-A-Service).
 
 ### Terminal & Input