fix: a notification's Configure button no longer opens system settings

The kernel memory killer's "Memory Shortage Avoided" notice carried a
Configure button that ran kcmshell6 and opened KDE's whole Notifications
settings under the teacher's account. Reproduced in the lab.

Plasma draws that button without consulting the Kiosk policy, but
kcmshell6 and System Settings do: every settings module Debian 13's
Plasma 6.3 installs (90) is now refused in the classroom's immutable
kdeglobals, so the same click shows only "disabled by the system
administrator". The clock's Configure Digital Clock goes with
plasma/allow_configure_when_locked=false; Configure Audio Devices
disappears on its own; the disabled window's Help button opened KDE Help
Center, which the package now conflicts with (plasma-desktop only
recommends it).

The maintenance terminal runs outside the classroom's configuration and
still opens every module, verified. converged-check fails if any module
on a machine is ever left unrestricted: 126 passed in the lab.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

config/plasma/xdg/kdeglobals

@@ -26,6 +26,12 @@ editable_desktop_icons=false
 editable_bookmarks=false
 movable_toolbars=false
 plasma/plasmashell/unlockedDesktop=false
+# A locked panel still offered "Configure Digital Clock…" on the clock's
+# right-click menu — measured on Plasma 6.3. This is Plasma's own key for
+# "no widget settings while the desktop is locked", and with it that entry
+# is gone. (The clock's "Adjust Date and Time…" stays, and opens a System
+# Settings with nothing in it: every module is restricted below.)
+plasma/allow_configure_when_locked=false
 plasma-desktop/scripting_console=false
 # Nothing in the classroom should offer to file a bug or open a manual.
 action/help_report_bug=false
@@ -47,6 +53,115 @@ action/help_contents=false
 # is not shown doors that will not open.
 [KDE Control Module Restrictions][$i]
 kcm_networkmanagement=false
+#
+# AND EVERY OTHER SETTINGS MODULE. A notification's Configure button —
+# measured on Plasma 6.3, from the "Memory Shortage Avoided" notice the
+# kernel's memory killer raised — runs `kcmshell6 notifications`, which
+# opened KDE's whole notification settings under the teacher's account:
+# every application and system service, with Apply. The notification
+# applet draws that button without asking this group; kcmshell6 and
+# System Settings do ask it, and with the module listed here the same
+# click opens only "The module kcm_notifications is disabled ... by the
+# system administrator". Measured.
+#
+# KDE has no wildcard for this, so the list is every module installed by
+# Debian 13's Plasma 6.3, as found on the lab machine. A teacher has a use
+# for none of them. tools/lab/converged-check fails if a module is ever
+# installed that is not listed here, so a Plasma update cannot quietly
+# reopen a door.
+#
+# The maintenance terminal is untouched: it runs with
+# XDG_CONFIG_DIRS=/etc/xdg, outside this file, so System Settings started
+# from it is the whole of System Settings.
+kcm_about-distro=false
+kcm_access=false
+kcm_activities=false
+kcm_audio_information=false
+kcm_autostart=false
+kcm_baloofile=false
+kcm_block_devices=false
+kcm_bluetooth=false
+kcm_bolt=false
+kcm_clock=false
+kcm_colors=false
+kcm_componentchooser=false
+kcm_cpu=false
+kcm_cursortheme=false
+kcm_desktoppaths=false
+kcm_desktoptheme=false
+kcm_device_automounter=false
+kcm_disks=false
+kcm_edid=false
+kcm_egl=false
+kcm_energyinfo=false
+kcm_feedback=false
+kcm_filetypes=false
+kcm_firewall=false
+kcm_firmware_security=false
+kcm_fontinst=false
+kcm_fonts=false
+kcm_gamecontroller=false
+kcm_glx=false
+kcm_icons=false
+kcm_interrupts=false
+kcm_kded=false
+kcm_keyboard=false
+kcm_keys=false
+kcm_kgamma=false
+kcm_krunner_kill=false
+kcm_krunnersettings=false
+kcm_kscreen=false
+kcm_kwallet5=false
+kcm_kwin_effects=false
+kcm_kwin_scripts=false
+kcm_kwin_virtualdesktops=false
+kcm_kwindecoration=false
+kcm_kwinoptions=false
+kcm_kwinrules=false
+kcm_kwinscreenedges=false
+kcm_kwinsupportinfo=false
+kcm_kwintabbox=false
+kcm_kwintouchscreen=false
+kcm_kwinxwayland=false
+kcm_landingpage=false
+kcm_lookandfeel=false
+kcm_memory=false
+kcm_mouse=false
+kcm_netpref=false
+kcm_network=false
+kcm_nightlight=false
+kcm_notifications=false
+kcm_opencl=false
+kcm_pci=false
+kcm_plasmasearch=false
+kcm_powerdevilprofilesconfig=false
+kcm_proxy=false
+kcm_pulseaudio=false
+kcm_qtquicksettings=false
+kcm_recentFiles=false
+kcm_regionandlang=false
+kcm_samba=false
+kcm_screenlocker=false
+kcm_sddm=false
+kcm_smserver=false
+kcm_solid_actions=false
+kcm_soundtheme=false
+kcm_splashscreen=false
+kcm_style=false
+kcm_tablet=false
+kcm_touchpad=false
+kcm_touchscreen=false
+kcm_usb=false
+kcm_users=false
+kcm_virtualkeyboard=false
+kcm_vulkan=false
+kcm_wallpaper=false
+kcm_wayland=false
+kcm_webshortcuts=false
+kcm_workspace=false
+kcm_xserver=false
+kcmspellchecking=false
+kwincompositing=false
 
 # Not immutable. Marking this group [$i] froze the colour scheme so hard
 # that `classroom-theme light` changed the running session and then lost