refactor: 5 architectural improvements (Tasks 2-5 + Task 6 fix)

- feat(domain): Hashtag value object with canonical extract() — unifies two
  divergent private implementations; fields pre-compute raw/normalized/url_slug/ap_name

- feat(presentation): Deps<S: FromAppState> extractor — each handler now
  declares its exact dependency surface; AppState unchanged; handlers
  become unit-testable without mocking all 20 deps

- refactor(feed): replace 5 flat FeedRepository methods with FeedQuery/FeedScope
  — single query() method; SQL shared logic lives once; adding feed types
  no longer requires 5 edits

- refactor(activitypub): ActivityPubRepository + OutboundFederationPort moved
  out of domain::ports into activitypub-base::ap_ports — domain crate no
  longer knows about AP IDs, inboxes, or actor URLs

- fix(outbox): OutboxRelay now opens a per-row transaction so FOR UPDATE
  SKIP LOCKED actually holds the lock during publish + mark_delivered

crates/application/src/services/federation_event.rs

@@ -1,8 +1,9 @@
+use activitypub_base::{ActivityPubRepository, OutboundFederationPort};
 use domain::{
     errors::DomainError,
     events::DomainEvent,
     models::thought::Visibility,
-    ports::{ActivityPubRepository, OutboundFederationPort, ThoughtRepository, UserReader},
+    ports::{ThoughtRepository, UserReader},
     value_objects::ThoughtId,
 };
 use std::sync::Arc;
@@ -212,13 +213,14 @@ impl FederationEventService {
 #[cfg(test)]
 mod tests {
     use super::*;
+    use activitypub_base::{ActorApUrls, OutboundFederationPort};
     use async_trait::async_trait;
+    use crate::testing::TestApRepo;
     use domain::{
         errors::DomainError,
         events::DomainEvent,
         models::thought::{Thought, Visibility},
         models::user::User,
-        ports::{ActivityPubRepository, OutboundFederationPort},
         testing::TestStore,
         value_objects::*,
     };
@@ -325,12 +327,23 @@ mod tests {
     }
 
     fn svc(store: &TestStore, spy: Arc<SpyPort>) -> FederationEventService {
+        let ap_repo = TestApRepo::new(store.clone());
         FederationEventService {
             thoughts: Arc::new(store.clone()),
             users: Arc::new(store.clone()),
             ap: spy,
             base_url: "https://example.com".to_string(),
-            ap_repo: Arc::new(store.clone()),
+            ap_repo: Arc::new(ap_repo),
+        }
+    }
+
+    fn svc_with_ap(store: &TestStore, ap_repo: TestApRepo, spy: Arc<SpyPort>) -> FederationEventService {
+        FederationEventService {
+            thoughts: Arc::new(store.clone()),
+            users: Arc::new(store.clone()),
+            ap: spy,
+            base_url: "https://example.com".to_string(),
+            ap_repo: Arc::new(ap_repo),
         }
     }
 
@@ -452,7 +465,8 @@ mod tests {
         let alice = alice();
         let mut thought = local_thought(alice.id.clone());
         thought.local = false;
-        store.thought_ap_ids.lock().unwrap().insert(
+        let ap_repo = TestApRepo::new(store.clone());
+        ap_repo.inner.thought_ap_ids.lock().unwrap().insert(
             thought.id.clone(),
             "https://mastodon.social/users/bob/statuses/123".into(),
         );
@@ -460,7 +474,7 @@ mod tests {
         store.thoughts.lock().unwrap().push(thought.clone());
 
         let spy = Arc::new(SpyPort::default());
-        svc(&store, spy.clone())
+        svc_with_ap(&store, ap_repo, spy.clone())
             .process(&DomainEvent::BoostAdded {
                 boost_id: BoostId::new(),
                 user_id: alice.id.clone(),
@@ -604,14 +618,15 @@ mod tests {
         let alice = alice();
         let mut thought = local_thought(alice.id.clone());
         thought.local = false;
-        store.thought_ap_ids.lock().unwrap().insert(
+        let ap_repo = TestApRepo::new(store.clone());
+        ap_repo.inner.thought_ap_ids.lock().unwrap().insert(
             thought.id.clone(),
             "https://mastodon.social/users/bob/statuses/456".into(),
         );
         store.thoughts.lock().unwrap().push(thought.clone());
 
         let spy = Arc::new(SpyPort::default());
-        svc(&store, spy.clone())
+        svc_with_ap(&store, ap_repo, spy.clone())
             .process(&DomainEvent::BoostRemoved {
                 user_id: alice.id.clone(),
                 thought_id: thought.id.clone(),
@@ -673,28 +688,28 @@ mod tests {
             PasswordHash("h".into()),
         );
         author.local = false;
-        store.actor_ap_urls.lock().unwrap().insert(
-            author.id.clone(),
-            domain::ports::ActorApUrls {
-                ap_id: "https://mastodon.social/users/author".into(),
-                inbox_url: "https://mastodon.social/users/author/inbox".into(),
-            },
-        );
-
         let thought = local_thought(author.id.clone());
-        store.thought_ap_ids.lock().unwrap().insert(
-            thought.id.clone(),
-            "https://mastodon.social/posts/123".into(),
-        );
-
         let liker = alice();
 
         store.users.lock().unwrap().push(author.clone());
         store.users.lock().unwrap().push(liker.clone());
         store.thoughts.lock().unwrap().push(thought.clone());
 
+        let ap_repo = TestApRepo::new(store.clone());
+        ap_repo.actor_ap_urls.lock().unwrap().insert(
+            author.id.clone(),
+            ActorApUrls {
+                ap_id: "https://mastodon.social/users/author".into(),
+                inbox_url: "https://mastodon.social/users/author/inbox".into(),
+            },
+        );
+        ap_repo.inner.thought_ap_ids.lock().unwrap().insert(
+            thought.id.clone(),
+            "https://mastodon.social/posts/123".into(),
+        );
+
         let spy = Arc::new(SpyPort::default());
-        svc(&store, spy.clone())
+        svc_with_ap(&store, ap_repo, spy.clone())
             .process(&DomainEvent::LikeAdded {
                 like_id: LikeId::new(),
                 user_id: liker.id,