fix(error): migrate notifications.rs + message-adapters error handling

src-tauri/src/commands/notifications.rs

@@ -1,8 +1,10 @@
 // Notification commands — desktop notification via notify-rust
 
+use crate::error::AppError;
 use crate::notifications;
 
 #[tauri::command]
-pub fn notify_desktop(title: String, body: String, urgency: String) -> Result<(), String> {
+pub fn notify_desktop(title: String, body: String, urgency: String) -> Result<(), AppError> {
     notifications::send_desktop_notification(&title, &body, &urgency)
+        .map_err(AppError::internal)
 }