docs(hm-core): TODO to return Url from api_url/app_url when the SDK allows

The harmont-cloud client string-concatenates its base (format!("{base}{path}")),
so BackendDomain must hand back a trailing-slash-trimmed String. Note to switch
to Url once the client accepts a URL base.

Author: markovejnovic

crates/hm-core/src/config/domain.rs

@@ -49,6 +49,10 @@ impl BackendDomain {
         Ok(Self(Url::parse(&normalized)?))
     }
 
+    // TODO: return `Url` from api_url()/app_url() once the harmont-cloud client
+    // accepts a URL base instead of string-concatenating (`format!("{base}{path}")`).
+    // Its naive concat is why these must hand back a trailing-slash-trimmed String.
+
     /// The API base URL (`https://api.<domain>`), without a trailing slash.
     #[must_use]
     pub fn api_url(&self) -> String {