fix: User checks (#139)

* check uniqueness on create and register user

* change user email, reserve release unique email

* usergrant unique aggregate

* usergrant uniqueness

* validate UserGrant

* fix tests

internal/project/model/project.go

@@ -20,6 +20,7 @@ type ProjectState int32
 const (
 	PROJECTSTATE_ACTIVE ProjectState = iota
 	PROJECTSTATE_INACTIVE
+	PROJECTSTATE_REMOVED
 )
 
 func NewProject(id string) *Project {