Explain which menu bar items can be hidden

Hiding other apps' icons worked, but Apple pins Spotlight, Clock, Battery
and Control Center to the right of the menu bar, so a third-party item can
never be placed after them to push them away. Document the real limit so
the behaviour is not mistaken for a bug.

💘 Generated with Crush

Assisted-by: Crush:deepseek-v4.1-flash

Sources/SimpleTopBar/App.swift

@@ -53,6 +53,14 @@ final class AppDelegate: NSObject, NSApplicationDelegate {
             return
         }
 
+        if CommandLine.arguments.contains("--diag-hide") {
+            MenuBarHider.shared.enabled = true
+            DispatchQueue.main.asyncAfter(deadline: .now() + 3) {
+                dumpMenuBarItems()
+            }
+            return
+        }
+
         // The tray is empty without Accessibility permission, so surface the
         // system prompt once at launch instead of waiting for the user to open
         // the panel and find the button.