feat(rss): implement RSS feed adapter and integrate with application state

crates/presentation/src/state.rs

@@ -2,10 +2,11 @@ use std::sync::Arc;
 
 use application::context::AppContext;
 
-use crate::ports::HtmlRenderer;
+use crate::ports::{HtmlRenderer, RssFeedRenderer};
 
 #[derive(Clone)]
 pub struct AppState {
     pub app_ctx: AppContext,
     pub html_renderer: Arc<dyn HtmlRenderer>,
+    pub rss_renderer: Arc<dyn RssFeedRenderer>,
 }