refactor: standardise S3 URL generation (#362)

* refactor: replace presigned URL uploads with backend upload endpoints

* feat: update avatar upload to use new endpoint

* refactor: use createS3Client in auth hooks

* feat: generate presigned URLs for avatars

* fix: show avatar image in user menu

* fix: hide tooltip if content is empty

* fix: support external avatar URLs in generateAvatarUrl

* fix: remove content type restriction on attachments

apps/web/src/components/Avatar.tsx

@@ -25,7 +25,7 @@ const Avatar = ({
   icon?: React.ReactNode;
   isLoading?: boolean;
 }) => {
-  const initials = name
+  const initials = name?.trim()
     ? getInitialsFromName(name)
     : inferInitialsFromEmail(email);