fix: explain notification permission state instead of failing silently

requestAuthorization only shows the system prompt once ever; when
permission is already denied it silently returns false and the checkbox
just snapped off with no explanation. toggleNotify now checks the
authorization status first: already-authorized enables directly,
not-determined triggers the system prompt (errors surfaced in an
alert), and denied shows an alert with an Open System Settings button
pointing at the Notifications pane.

Also adds a UNUserNotificationCenterDelegate so banners are shown even
while BrewBar is the active app — otherwise macOS suppresses them,
which reads as "notifications don't work" right after enabling.

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

BrewBar/BrewBarApp.swift

@@ -47,6 +47,7 @@ class AppDelegate: NSObject, NSApplicationDelegate {
 
     func applicationDidFinishLaunching(_: Notification) {
         Settings.registerDefaults()
+        UNUserNotificationCenter.current().delegate = self
 
         statusItem = NSStatusBar.system.statusItem(withLength: NSStatusItem.variableLength)
         statusItem.button?.imagePosition = .imageLeft // icon stays visible next to the count
@@ -437,3 +438,14 @@ class AppDelegate: NSObject, NSApplicationDelegate {
         logWindow?.update(text: logBuffer)
     }
 }
+
+extension AppDelegate: UNUserNotificationCenterDelegate {
+    /// Without this, macOS suppresses banners while BrewBar is the active
+    /// app (e.g. right after toggling the setting with the window open).
+    func userNotificationCenter(_: UNUserNotificationCenter,
+                                willPresent _: UNNotification,
+                                withCompletionHandler completionHandler: @escaping (UNNotificationPresentationOptions) -> Void)
+    {
+        completionHandler([.banner])
+    }
+}

BrewBar/SettingsWindowController.swift

@@ -246,15 +246,62 @@ class SettingsWindowController: NSWindowController {
             return
         }
 
-        UNUserNotificationCenter.current().requestAuthorization(options: [.alert]) { granted, _ in
+        // requestAuthorization only shows the system prompt the first time
+        // ever; if permission was denied before, it silently returns false.
+        // Check the status first so the user learns what actually happened.
+        let center = UNUserNotificationCenter.current()
+        center.getNotificationSettings { notificationSettings in
             // callback arrives on a background queue; UI needs main
             DispatchQueue.main.async {
-                Settings.notifyOnNewUpdates = granted
-                sender.state = granted ? .on : .off
+                switch notificationSettings.authorizationStatus {
+                case .authorized, .provisional:
+                    Settings.notifyOnNewUpdates = true
+
+                case .notDetermined:
+                    center.requestAuthorization(options: [.alert, .sound]) { granted, error in
+                        DispatchQueue.main.async {
+                            Settings.notifyOnNewUpdates = granted
+                            sender.state = granted ? .on : .off
+                            if let error {
+                                self.showNotificationProblem(error.localizedDescription)
+                            }
+                        }
+                    }
+
+                case .denied:
+                    sender.state = .off
+                    self.showNotificationsDenied()
+
+                @unknown default:
+                    sender.state = .off
+                }
             }
         }
     }
 
+    func showNotificationsDenied() {
+        let alert = NSAlert()
+        alert.alertStyle = .warning
+        alert.messageText = "Notifications are disabled for BrewBar"
+        alert.informativeText = "macOS has notifications turned off for BrewBar. Enable them in System Settings > Notifications > BrewBar, then flip this switch again."
+        alert.addButton(withTitle: "Open System Settings")
+        alert.addButton(withTitle: "Cancel")
+
+        if alert.runModal() == .alertFirstButtonReturn,
+           let url = URL(string: "x-apple.systempreferences:com.apple.Notifications-Settings.extension")
+        {
+            NSWorkspace.shared.open(url)
+        }
+    }
+
+    func showNotificationProblem(_ message: String) {
+        let alert = NSAlert()
+        alert.alertStyle = .warning
+        alert.messageText = "Could not enable notifications"
+        alert.informativeText = message
+        alert.runModal()
+    }
+
     @objc func toggleShowCount(_ sender: NSButton) {
         Settings.showCountInMenuBar = sender.state == .on
         appDelegate?.updateMenuBarCount() // reflect immediately, no refetch needed