feat: give every room the broker, one scale, and its own panel back

Little Waders took the Plasma build and reported what a container
cannot. A disc player on a machine with no optical drive, a clock nobody
at the back of the room could read, a browser at half the size of the
panel around it, and Parent Call with no broker to call.

The broker is the same for every classroom, so it is a default now and
not something to fill in room by room. classroom-migrate brings an
existing room to the same place without touching its name, its username
or its password, and Parent Call distinguishes a broker it cannot reach
from one that was never set up: those send somebody to look at
completely different things.

The disc player's detection was right and ran too late — alongside the
session rather than before it, and the panel is built from the layout the
moment a session starts. It runs before the display manager now, and
again from udev when a drive is plugged in.

UI_SCALE had a ceiling of 1.5, which cannot express a 4K television; a
clock pinned at 15 points, which is the same size at every scale; and a
browser that was never told the number at all. All three are fixed and
the room doubles together at 200%.

This also brings 0.1.47's work into the repository, where it had only
ever existed in a build directory under /tmp: the hidden display dialog,
its authenticated writer, the polkit action, and the church's own
wallpaper. One piece of it is deliberately left out. The custom volume
display needed a shell package of our own, and with one selected
plasmashell builds no panel at all — measured twice, with that build's
own files, on a classroom that deletes its panel configuration at every
login by design.

The lab connected to the real church broker the moment the package
defaulted to it. Nothing was left behind, which was checked, but the
guard that should have stopped it had never worked: it used iptables,
which the lab image does not have, and probed with /dev/tcp under dash,
where that always fails. Both reported success.

Co-Authored-By: Claude Opus 5 <[email protected]>

tools/build-release.sh

@@ -207,7 +207,8 @@ install -Dm644 \
 # Not /etc/xdg: plasma-workspace already owns files by these names there.
 # The classroom's directory goes in front of it in XDG_CONFIG_DIRS instead.
 for setting in kwinrc kwinrulesrc kscreenlockerrc ksmserverrc \
-        krunnerrc plasmanotifyrc powermanagementprofilesrc; do
+        krunnerrc plasmanotifyrc powermanagementprofilesrc plasmarc \
+        plasmaparc; do
     install -Dm644 \
         "$ROOT/config/plasma/xdg/${setting}" \
         "$STAGE/etc/ekklesia-classroom/xdg/${setting}"
@@ -258,6 +259,32 @@ install -Dm644 \
     "$ROOT/config/plasma/lookandfeel/contents/layouts/org.kde.plasma.desktop-layout.js" \
     "$LOOK/contents/layouts/org.kde.plasma.desktop-layout.js"
 
+# NO SHELL PACKAGE OF OUR OWN.
+#
+# Plasma 6.3 loads the volume display from the shell package and from
+# nowhere else — the look and feel is not consulted, which was measured —
+# so a shell package is the only supported way to replace it, and a
+# classroom-sized one was built and tried. With it selected, plasmashell
+# builds no panel at all: not the stock one, not ours. Measured twice, and
+# the room's panel is deleted at every login on purpose, so every login
+# would have come up with nothing on the screen.
+#
+# The volume display is Plasma's own instead. UI_SCALE makes it the right
+# size on a television, which is what the room actually needed.
+
+# The room's Plasma style: the card a notification and the volume display
+# are drawn on. Only the pieces the classroom changes; everything else
+# comes from Breeze, so this can never leave a popup undrawn.
+STYLE="$STAGE/usr/share/plasma/desktoptheme/ekklesia"
+
+install -Dm644 \
+    "$ROOT/config/plasma/desktoptheme/metadata.json" \
+    "$STYLE/metadata.json"
+
+install -Dm644 \
+    "$ROOT/config/plasma/desktoptheme/dialogs/background.svg" \
+    "$STYLE/dialogs/background.svg"
+
 for entry in "$ROOT"/config/plasma/applications/*.desktop; do
     install -Dm644 "$entry" \
         "$STAGE/usr/share/applications/$(basename "$entry")"
@@ -339,6 +366,38 @@ install -Dm755 \
     "$ROOT/scripts/classroom-migrate" \
     "$STAGE/usr/local/bin/classroom-migrate"
 
+# One number, one place to ask for it.
+install -Dm755 \
+    "$ROOT/scripts/classroom-ui-scale" \
+    "$STAGE/usr/local/bin/classroom-ui-scale"
+
+# The room's display size: a hidden dialog behind a chord, a writer that
+# asks for an administrator password, and the one thing that applies the
+# answer at every login.
+for command in classroom-display-settings classroom-set-scale; do
+    install -Dm755 \
+        "$ROOT/scripts/${command}" \
+        "$STAGE/usr/local/bin/${command}"
+done
+
+install -Dm644 \
+    "$ROOT/config/polkit/org.ekklesia.classroom.display.policy" \
+    "$STAGE/usr/share/polkit-1/actions/org.ekklesia.classroom.display.policy"
+
+install -Dm644 \
+    "$ROOT/config/plasma/autostart/ekklesia-classroom-scale.desktop" \
+    "$STAGE/etc/xdg/autostart/ekklesia-classroom-scale.desktop"
+
+# The panel's disc player follows this machine's hardware, and the
+# detection has to have happened before a session starts.
+install -Dm644 \
+    "$ROOT/systemd/layout/ekklesia-classroom-layout.service" \
+    "$STAGE/etc/systemd/system/ekklesia-classroom-layout.service"
+
+install -Dm644 \
+    "$ROOT/config/udev/60-ekklesia-classroom-optical.rules" \
+    "$STAGE/etc/udev/rules.d/60-ekklesia-classroom-optical.rules"
+
 install -Dm644 \
     "$ROOT/lib/classroom_audio.py" \
     "$STAGE/usr/local/lib/ekklesia-classroom/classroom_audio.py"