fix(rss): absolute item/channel links, atom self, application/xml

crates/domain/src/ports/rss.rs

@@ -1,5 +1,19 @@
 use crate::models::DiaryEntry;
 
-pub trait RssFeedRenderer: Send + Sync {
-    fn render_feed(&self, entries: &[DiaryEntry], title: &str) -> Result<String, String>;
+/// Channel-level metadata for a rendered feed. Paths are site-relative
+/// (e.g. `/users/{id}`); the renderer resolves them against its base URL.
+pub struct FeedChannel<'a> {
+    pub title: &'a str,
+    /// Human-readable page the channel represents.
+    pub link_path: &'a str,
+    /// Where the feed itself is served, advertised as `atom:link rel="self"`.
+    pub self_path: &'a str,
+}
+
+pub trait RssFeedRenderer: Send + Sync {
+    fn render_feed(
+        &self,
+        entries: &[DiaryEntry],
+        channel: &FeedChannel<'_>,
+    ) -> Result<String, String>;
 }