fix: remote actor display names in thought cards — use last URL segment as username, resolve display_name after intern

crates/domain/src/ports.rs

@@ -342,6 +342,14 @@ pub trait ActivityPubRepository: Send + Sync {
     /// Idempotent — safe to call multiple times with the same URL.
     async fn intern_remote_actor(&self, actor_ap_url: &url::Url) -> Result<UserId, DomainError>;
 
+    /// Update display_name and avatar_url for an already-interned remote actor.
+    async fn update_remote_actor_display(
+        &self,
+        user_id: &UserId,
+        display_name: Option<&str>,
+        avatar_url: Option<&str>,
+    ) -> Result<(), DomainError>;
+
     // ── Inbox processing (remote → local) ───────────────────────────
 
     /// Persist an incoming remote Note. Idempotent on ap_id.

crates/domain/src/testing.rs

@@ -779,6 +779,14 @@ impl ActivityPubRepository for TestStore {
         self.users.lock().unwrap().push(user);
         Ok(uid)
     }
+    async fn update_remote_actor_display(
+        &self,
+        _user_id: &UserId,
+        _display_name: Option<&str>,
+        _avatar_url: Option<&str>,
+    ) -> Result<(), DomainError> {
+        Ok(())
+    }
     async fn accept_note(
         &self,
         _ap_id: &url::Url,