Added NoteStore interface, mock and repository with Create method

internal/repository/notestore.go

@@ -3,6 +3,7 @@ package repository
 import (
 	"git.hrafn.xyz/aether/notes/internal/models"
 )
+
 type NoteStore interface {
 	SaveNote(models.Note) (models.Note, error)
-}
+}