feat: add user preference for audio notifications and play sound on new alerts

- Added sound_enabled column to users table with a default of true.

- Implemented a pleasant pop sound (notification.mp3) that plays when a new unread notification arrives.

- Added a toggle in the User Profile page allowing users to enable/disable the sound.

types.ts

@@ -18,6 +18,7 @@ export interface User {
   team_id: string;
   bio?: string;
   status: 'active' | 'inactive';
+  sound_enabled?: boolean;
 }
 
 export interface Attendance {