Turn a website into an application, and notice the charger

Two of Section E's small wins.

panama-webapp gives a site its own icon, its own window with no browser
chrome, and its own launcher entry, which is most of what "installed"
means in practice and what both macOS and Windows now ship. It scrapes
the site's apple-touch-icon, falls back twice, and never fails an
install over a favicon: a web app with a generic icon still works.
Names are slugged, so "../../../../tmp/pwn" lands inside the
applications directory as tmp-pwn rather than anywhere else, and
remove refuses anything without the marker it writes -- sharing a name
with a real application must not delete that application. A browser
that cannot do app mode is told so rather than handed something that
opens an ordinary window and pretends.

The charger now announces itself through StatusEvents, which was
already the right layer and only wanted a producer. Ambient priority,
so Do Not Disturb quiets it, because a charger is exactly what DND is
for. A critically low battery is published at a priority DND does not
silence, because the one message you must not miss is the one saying
the machine is about to stop. Both join the existing silent-startup
window rather than announcing the state they found.

The keyboard-layout toast the plan also listed is deliberately not
built. Hyprland exposes the active keymap but not a change event
Quickshell already consumes, so it would need either polling or new
event plumbing, and this machine has one layout and could not test it.

tests/quickshell/panama-commands-contract

@@ -77,7 +77,7 @@ declare -a standalone=(
     lock-screen suspend-system log-out reboot-system power-off
     remind-me list-reminders pick-color
     switch-window force-quit-window kill-process ssh-hosts recent-files
-    copy-password keyboard-shortcuts show-welcome
+    copy-password keyboard-shortcuts show-welcome install-web-app
 )
 
 # Generated commands must match their source. A stale command dispatches to a