docs(wiki): runbook §5c uses gpasswd -d — deluser rejects hyphenated users

Demoting the operator on park-buzi failed with "sanitize_string: invalid
characters in 'park-operator'" — Ubuntu's perl adduser/deluser tooling
rejects the hyphenated username. §5c now prescribes gpasswd -d for
sudo/lxd/lpadmin (shadow-suite, no perl sanitize) and documents that
group removal lands at NEXT login: the auto-login operator session keeps
its old memberships until reboot/relog, so verify `groups` from inside
the session afterwards.

Claude-Session: https://claude.ai/code/session_01Xcm6ikLgGoCxxHrxtjkk5V

wiki/log.md

@@ -2459,3 +2459,11 @@ stays attributable in the chain. Best-effort: no build/key → loud warning, see
 (verified both paths on a scratch DB). [[appliance-provisioning]] gained §7e: FORCE=1 reset
 commands (interactive preferred — keeps the password out of shell history), sessions-not-revoked
 caveat + JWT_SECRET rotation for suspected theft, role-row self-heal note added to §7d.
+
+## [2026-07-06] update | Runbook §5c: gpasswd -d, not deluser (hyphenated-username perl bug)
+
+Demoting the operator on park-buzi hit `sanitize_string: invalid characters in 'park-operator'` —
+Ubuntu's perl adduser/deluser tooling rejects the hyphenated username. [[appliance-provisioning]]
+§5c now uses `gpasswd -d <operator> sudo|lxd|lpadmin` (shadow-suite, no perl sanitize) and notes
+that group removal applies at NEXT login — the auto-login operator session keeps old memberships
+until reboot/relog, so verify `groups` from inside the session afterwards.