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/shell.qml

@@ -896,6 +896,14 @@ ShellRoot {
       return "ok"
     }
 
+    function toggleBarTransparency(): string {
+      if (shell.bar && typeof shell.bar.toggleTransparency === "function") {
+        shell.bar.toggleTransparency()
+        return "ok"
+      }
+      return "no-bar"
+    }
+
     function setPluginEnabled(id: string, enabled: string): string {
       return shell.pluginRegistry.setEnabled(id, enabled === "true") ? "ok" : "unknown"
     }