refactor: remaining MEDIUM — CQRS splits, DI Deps, profile dedup, event Value, response enum

M1: MovieRepository→MovieCommand/MovieQuery, WatchEventRepository→
WatchEventCommand/WatchEventQuery
M2: goals/ and import/ use Deps structs
M7: extract upload_image helper in update_profile
M8: FederationDeliveryRequested activity_json String→serde_json::Value
M11: UserProfileResponse uses ProfileViewData enum

crates/adapters/activitypub/src/federation_event_bridge.rs

@@ -34,12 +34,10 @@ impl k_ap::EventPublisher for FederationEventBridge {
                 activity,
                 signing_actor_id,
             } => {
-                let json = serde_json::to_string(&activity)
-                    .map_err(|e| anyhow::anyhow!("serialize activity: {e}"))?;
                 self.domain_publisher
                     .publish(&DomainEvent::FederationDeliveryRequested {
                         inbox_url: inbox.to_string(),
-                        activity_json: json,
+                        activity_json: activity,
                         signing_actor_id,
                     })
                     .await