feat(user): use name for initals avatar, not username

For external auth providers, the username might be randomly generated,
which results in a random initial - this is unexpected and confusing for
users.

pkg/modules/avatar/initials/initials.go

@@ -143,7 +143,7 @@ func getAvatarForUser(u *user.User) (fullSizeAvatar *image.RGBA64, err error) {
 
 	if !exists {
 		log.Debugf("Initials avatar for user %d not cached, creating...", u.ID)
-		firstRune := []rune(strings.ToUpper(u.Username))[0]
+		firstRune := []rune(strings.ToUpper(u.Name))[0]
 		bg := avatarBgColors[int(u.ID)%len(avatarBgColors)] // Random color based on the user id
 
 		fullSizeAvatar, err = drawImage(firstRune, bg)

pkg/routes/api/v1/user_settings.go

@@ -144,6 +144,10 @@ func ChangeUserAvatarProvider(c echo.Context) error {
 		return handler.HandleHTTPError(err)
 	}
 
+	if user.AvatarProvider == "initials" {
+		avatar.FlushAllCaches(user)
+	}
+
 	if err := s.Commit(); err != nil {
 		_ = s.Rollback()
 		return handler.HandleHTTPError(err)