Merge PR: fix(desktop): make Enable OS notifications button actually enable them

Merges nostr proposal 82e72369 into main:
- Provide LocalNotificationSettings / LocalNotificationReadState at the app
  root. Both CompositionLocals were already consumed by NotificationsScreen
  and NotificationSettingsScreen but never provided, so each screen fell back
  to its own PreferencesNotificationSettings(); disk prefs stayed in sync but
  the in-memory StateFlow updates never crossed instances.
- Flip the master toggle when the OS permission is granted, so the "Enable OS
  notifications" button matches its label end to end.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

desktopApp/src/jvmMain/kotlin/com/vitorpamplona/amethyst/desktop/Main.kt

@@ -1262,11 +1262,32 @@ private fun AppInner(
                 // Auto-dispatcher: subscribes to newEventBundles and fires OS toasts.
                 // Only starts once the user is logged in — pubKey and settings must exist.
                 val loggedIn = accountState as? AccountState.LoggedIn
+                // Single, process-wide NotificationSettings instance. Hoisted here (not
+                // inside NotificationSettingsScreen / NotificationsScreen) so the
+                // settings UI, the inbox column's OS-toasts banner, and the auto-
+                // dispatcher all read + write the same MutableStateFlow. Without this,
+                // each screen fell back to its own PreferencesNotificationSettings()
+                // instance — the disk-backed prefs stayed in sync, but the in-memory
+                // StateFlow updates never crossed instances, so toggling the master
+                // switch or granting permission never actually notified the auto-
+                // dispatcher until the app restarted.
                 val notifSettings =
                     remember {
                         com.vitorpamplona.amethyst.commons.moderation.notifications
                             .PreferencesNotificationSettings()
                     }
+                // Per-account read-state for the notification inbox. Keyed on
+                // pubKey so switching accounts gets a fresh cursor. `remember` here
+                // is intentionally keyed on pubKeyHex; a null pubKey (Loading /
+                // LoggedOut branches never render the settings screen anyway, but
+                // guard against a stale ReadState leaking between accounts).
+                val notifReadState =
+                    remember(loggedIn?.pubKeyHex) {
+                        loggedIn?.pubKeyHex?.let { pk ->
+                            com.vitorpamplona.amethyst.commons.moderation.notifications
+                                .PreferencesNotificationReadState(pk)
+                        }
+                    }
                 DisposableEffect(loggedIn?.pubKeyHex, notifDispatcher, localCache) {
                     val myPk = loggedIn?.pubKeyHex
                     val autoDispatcherJob =
@@ -1294,6 +1315,8 @@ private fun AppInner(
                     com.vitorpamplona.amethyst.desktop.service.drafts.LocalNoteDraftStore provides noteDraftStore,
                     LocalHashtagSpamSettings provides hashtagSpamSettings,
                     com.vitorpamplona.amethyst.desktop.ui.notifications.LocalNotificationDispatcher provides notifDispatcher,
+                    com.vitorpamplona.amethyst.desktop.ui.notifications.LocalNotificationSettings provides notifSettings,
+                    com.vitorpamplona.amethyst.desktop.ui.notifications.LocalNotificationReadState provides notifReadState,
                 ) {
                     when (accountState) {
                         is AccountState.Loading -> {

desktopApp/src/jvmMain/kotlin/com/vitorpamplona/amethyst/desktop/ui/settings/NotificationSettingsScreen.kt

@@ -183,9 +183,20 @@ fun NotificationSettingsScreen(onBack: (() -> Unit)? = null) {
                                         } finally {
                                             requestingPermission = false
                                         }
+                                    // Match the button label: "Enable OS notifications"
+                                    // must actually enable them end-to-end. Prior to this,
+                                    // clicking through the OS prompt granted permission
+                                    // but left the master toggle OFF, so the auto-
+                                    // dispatcher stayed muted and the user had to hunt
+                                    // for the switch above. Flip it here on grant — the
+                                    // switch UI observes settings.enabled and
+                                    // recomposes automatically.
+                                    if (newState == PermissionState.Granted && !enabled) {
+                                        settings.setEnabled(true)
+                                    }
                                     testStatus =
                                         when (newState) {
-                                            PermissionState.Granted -> "Permission granted. Try the test toast below."
+                                            PermissionState.Granted -> "Permission granted. Notifications are on — try the test toast below."
                                             PermissionState.Denied -> "Permission denied. Enable in System Settings if you change your mind."
                                             PermissionState.BundleRequired -> "Notifications need a bundled app — run `./gradlew :desktopApp:runDistributable`."
                                             else -> null