fix: content negotiation for followers/following — resolve AP router conflict

crates/domain/src/testing.rs

@@ -551,6 +551,22 @@ impl FederationActionPort for TestStore {
     async fn actor_json(&self, _user_id: &UserId) -> Result<String, DomainError> {
         Err(DomainError::NotFound)
     }
+
+    async fn followers_collection_json(
+        &self,
+        _user_id: &UserId,
+        _page: Option<u32>,
+    ) -> Result<String, DomainError> {
+        Err(DomainError::NotFound)
+    }
+
+    async fn following_collection_json(
+        &self,
+        _user_id: &UserId,
+        _page: Option<u32>,
+    ) -> Result<String, DomainError> {
+        Err(DomainError::NotFound)
+    }
 }
 
 #[async_trait]