refactor: extract view-model mappers from presentation handlers

Move mapping logic (domain→DTO/template structs) into mappers/ module.
Handlers now call mapper fns instead of inline conversions.

crates/presentation/src/mappers/users.rs

@@ -0,0 +1,42 @@
+use application::users::get_profile::PendingFollowerView;
+use domain::models::UserSummary;
+use domain::ports::RemoteActorInfo;
+use template_askama::{RemoteActorData, RemoteActorDisplay, UserSummaryView};
+
+pub fn user_summary_view(u: &UserSummary) -> UserSummaryView {
+    let name = u.email().split('@').next().unwrap_or("?").to_string();
+    let initial = name.chars().next().unwrap_or('?').to_ascii_uppercase();
+    let avg_display = u
+        .avg_rating
+        .map(|r| format!("{:.1}", r))
+        .unwrap_or_else(|| "\u{2014}".to_string());
+    let avatar_url = u.avatar_path.as_ref().map(|p| format!("/images/{}", p));
+    UserSummaryView {
+        user_id: u.user_id.value(),
+        display_name: name,
+        initial,
+        avg_rating_display: avg_display,
+        total_movies: u.total_movies,
+        avatar_url,
+    }
+}
+
+pub fn remote_actor_display(a: &RemoteActorInfo) -> RemoteActorDisplay {
+    let display = a.display_name.clone().unwrap_or_else(|| a.handle.clone());
+    let initial = display.chars().next().unwrap_or('?').to_ascii_uppercase();
+    RemoteActorDisplay {
+        handle: a.handle.clone(),
+        display_name: display,
+        initial,
+        url: a.url.clone(),
+    }
+}
+
+pub fn pending_follower_data(p: &PendingFollowerView) -> RemoteActorData {
+    RemoteActorData {
+        handle: p.handle.clone(),
+        url: p.url.clone(),
+        display_name: p.display_name.clone(),
+        avatar_url: p.avatar_url.clone(),
+    }
+}