full backend rewrite.

calling this v0.4.0

backend/src/api/profile.rs

@@ -0,0 +1,13 @@
+use rocket::State;
+use crate::api::auth::Session;
+use crate::error::ApiResult;
+use crate::svc::user_svc::UserService;
+
+#[get("/users/<id>")]
+pub async fn display_name(
+	id: i64,
+	_ag: Session,
+	svc: &State<UserService>,
+) -> ApiResult<String> {
+	svc.get_username(id).await
+}