Expose the shell's remaining UI-only toggles over IPC

Every toggle you could only reach by mouse or panel hotkey is now
scriptable through omarchy-shell:

- omarchy.bluetooth toggleBluetooth — the radio (was right-click / B)
- omarchy.network toggleNetwork — Wi-Fi on/off (was W in the panel)
- omarchy.tailscale toggleTailscale — the connection as one call,
  matching the widget's right-click, instead of separate up/down
- omarchy.clock toggleWeekStart — calendar week start (was W)
- shell toggleBarTransparency — the bar background (was manage UI only)

Bluetooth and network follow the power/monitor pattern: manageIpc: false
so the panel owns the target's single IpcHandler and can extend it past
the inherited lifecycle methods.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

shell/plugins/panels/clock/BarWidget.qml

@@ -73,6 +73,10 @@ BarWidget {
     if (panelLoader.item) panelLoader.item.toggle()
   }
 
+  function toggleWeekStart() {
+    if (panelLoader.item) panelLoader.item.toggleWeekStart()
+  }
+
   // The clock fills more slot than it paints a mark for, at both
   // orientations: horizontally it is a text label in a padded slot, so the
   // dot takes the label width; vertically it is a stack of icon-sized lines,
@@ -127,6 +131,7 @@ BarWidget {
 
     function refresh(): void { root.broadcast("refresh") }
     function cycleFormat(): void { root.cycleFormat() }
+    function toggleWeekStart(): void { root.toggleWeekStart() }
     function open(): void { root.open() }
     function close(): void { root.close() }
     function show(): void { root.open() }