feat(ap): handle Undo(Like) inbound activity

crates/adapters/activitypub-base/src/content.rs

@@ -52,6 +52,9 @@ pub trait ApObjectHandler: Send + Sync {
     /// `actor_url` is the AP URL of the remote actor who sent the Announce.
     async fn on_announce_received(&self, object_url: &Url, actor_url: &Url) -> anyhow::Result<()>;
 
+    /// Called when a remote actor removes a Like from a local thought.
+    async fn on_unlike(&self, object_url: &Url, actor_url: &Url) -> anyhow::Result<()>;
+
     /// Total number of locally-authored posts across all users.
     async fn count_local_posts(&self) -> anyhow::Result<u64>;
 }