Make Shell a category, the bar legible, and the dock a real dock

Desktop & Dock becomes Shell — Bar, Dock, Control Center, Tiling,
Workspaces — the home for everything Quickshell draws. The settings-
management cluster moves to System as Sync & Backup, Appearance's
Shell tab dissolves, and 24-hour time finally lives on Date & Time,
which always owned it.

The bar gets what it never had: a way to survive the wallpaper. A
second neutral text family (follow theme, or forced light or dark),
a one-layer shadow under every glyph, and a gradient scrim for
wallpapers nothing else survives — all off by default, pixel-identical
until asked. Widgets earn toggles (weather, media, clipboard, calendar
countdown), the vitals cluster stops leaving a dead pill behind, and
Control Center's sections learn to step aside.

The dock graduates from MVP: a context menu with window rows, pin,
unpin, quit and new-window; scroll an icon to cycle its windows; drag
to reorder on the dock itself; hover previews with one-shot captures;
and "Add App to Dock" in the launcher. Three real bugs died en route —
menus that slid away with the autohide, a readonly-property crash on
every menu open, and a drag that drifted half a slot per icon on side
docks. The pinned-apps editor in Settings becomes a drag strip.

166 contracts; the full suite is green except two live display and
switcher tests that cannot run behind a locked session — re-verified
on unlock.

Claude-Session: https://claude.ai/code/session_01Ms2FbjQy31TVf3CEvQhGM8

config/dot/quickshell/modules/settings/DateTimePage.qml

@@ -3,8 +3,10 @@
 // These belong to the machine rather than to Panama, so nothing here is stored
 // in Panama's settings file -- it would be a second answer to a question the
 // system already answers. Timezone and network time are read from and written
-// to timedatectl directly; the clock's presentation lives on Appearance,
-// because that genuinely is a Panama preference.
+// to timedatectl directly. 24-hour time is the one presentation choice that
+// belongs here rather than on Shell › Bar: it drives the date menu,
+// notification timestamps and the lock screen as well as the bar. The rest of
+// the bar clock's presentation -- seconds, weekday -- stays with the bar.
 //
 // Changing the timezone or network time needs privilege. timedatectl asks
 // polkit, and a canceled dialog surfaces as an error rather than as a value
@@ -30,6 +32,11 @@ SettingsPage {
             detail: DateTime.timezone === "" ? "Reading the system clock" : DateTime.timezone
             value: Qt.formatDateTime(clock.date, Settings.use24Hour ? "ddd d MMM  HH:mm" : "ddd d MMM  h:mm AP")
         }
+        // Not just the bar's. The same choice reads out in the date menu,
+        // every notification's timestamp, and the lock screen, so it belongs
+        // beside the clock the whole machine shares rather than on a page
+        // about one surface.
+        ToggleRow { setting: "use24Hour" }
         SettingRow {
             label: "Set automatically"
             detail: DateTime.ntpEnabled