fix: stop the fallback sound when notifications are denied

Implement fallbackEffects(_:authorizationState:) and route every
out-of-band fallback call site through it: FeedCoordinator's denied
branch, its just-declined-the-prompt branch, and the store's
unauthorized scheduleUserNotification fallback. Only .denied strips the
sound; .notDetermined (deferred prompt) and granted states keep the
audible fallback, and delivery-failure fallbacks for authorized users
are unchanged.

This is the TCC-independent half of #5650: the Focus assertion-store
gate cannot run on a default install (the store needs Full Disk
Access), but a user who turned cmux notifications off has already asked
for silence - including during Focus, which suppresses banners through
the same denied-shaped fallback. The Focus gate remains as best-effort
for FDA installs and the app-frontmost suppressed-banner path.

This is the green half: the denied-authorization test from the previous
commit now passes.

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

Author: austinywang

Sources/Feed/FeedCoordinator.swift

@@ -919,12 +919,17 @@ private extension FeedCoordinator {
                             effects: effects
                         )
                     } else {
+                        // The user declined the prompt just now: honor the
+                        // fresh denial on this very notification.
                         self.runFallbackEffectsIfStillAwaiting(
                             requestId: requestId,
                             title: title,
                             subtitle: subtitle,
                             body: body,
-                            effects: effects
+                            effects: TerminalNotificationStore.fallbackEffects(
+                                effects,
+                                authorizationState: .denied
+                            )
                         )
                     }
                 default:
@@ -933,7 +938,12 @@ private extension FeedCoordinator {
                         title: title,
                         subtitle: subtitle,
                         body: body,
-                        effects: effects
+                        effects: TerminalNotificationStore.fallbackEffects(
+                            effects,
+                            authorizationState: TerminalNotificationStore.authorizationState(
+                                from: settings.authorizationStatus
+                            )
+                        )
                     )
                 }
             }

Sources/TerminalNotificationQueue.swift

@@ -447,6 +447,9 @@ extension TerminalNotificationStore {
         _ effects: TerminalNotificationPolicyEffects,
         authorizationState: NotificationAuthorizationState
     ) -> TerminalNotificationPolicyEffects {
-        effects
+        guard authorizationState == .denied else { return effects }
+        var silenced = effects
+        silenced.sound = false
+        return silenced
     }
 }

Sources/TerminalNotificationStore.swift

@@ -2091,7 +2091,7 @@ final class TerminalNotificationStore: ObservableObject {
                     title: content.title,
                     subtitle: content.subtitle,
                     body: content.body,
-                    effects: effects
+                    effects: Self.fallbackEffects(effects, authorizationState: self.authorizationState)
                 )
                 return
             }