refactor: typed errors in rss/import ports

crates/adapters/rss/src/lib.rs

@@ -1,3 +1,4 @@
+use domain::errors::DomainError;
 use domain::models::DiaryEntry;
 use domain::ports::{FeedChannel, RssFeedRenderer};
 use rss_feed::extension::atom::{self, AtomExtensionBuilder, Link};
@@ -24,7 +25,7 @@ impl RssFeedRenderer for RssAdapter {
         &self,
         entries: &[DiaryEntry],
         channel: &FeedChannel<'_>,
-    ) -> Result<String, String> {
+    ) -> Result<String, DomainError> {
         let items = entries
             .iter()
             .map(|e| {