feat: implement merge readiness plan to close gaps between v2 and v1

- Task 1: Fix feed response hydration by adding `to_thought_response` helper and updating feed handlers to return full `ThoughtResponse`.
- Task 2: Wire follower/following REST routes for user feeds.
- Task 3: Add user listing and count endpoints, including `GET /users` and `GET /users/count`.
- Task 4: Implement popular tags feature with `GET /tags/popular`.
- Task 5: Enhance configuration with HOST, CORS_ORIGINS, and optional rate limiting using tower-governor.

crates/adapters/postgres/src/remote_actor.rs

@@ -1,10 +1,18 @@
 use async_trait::async_trait;
 use chrono::{DateTime, Utc};
+use domain::{
+    errors::DomainError, models::remote_actor::RemoteActor, ports::RemoteActorRepository,
+};
 use sqlx::PgPool;
-use domain::{errors::DomainError, models::remote_actor::RemoteActor, ports::RemoteActorRepository};
 
-pub struct PgRemoteActorRepository { pool: PgPool }
-impl PgRemoteActorRepository { pub fn new(pool: PgPool) -> Self { Self { pool } } }
+pub struct PgRemoteActorRepository {
+    pool: PgPool,
+}
+impl PgRemoteActorRepository {
+    pub fn new(pool: PgPool) -> Self {
+        Self { pool }
+    }
+}
 
 #[async_trait]
 impl RemoteActorRepository for PgRemoteActorRepository {
@@ -23,7 +31,15 @@ impl RemoteActorRepository for PgRemoteActorRepository {
 
     async fn find_by_url(&self, url: &str) -> Result<Option<RemoteActor>, DomainError> {
         #[derive(sqlx::FromRow)]
-        struct Row { url: String, handle: String, display_name: Option<String>, inbox_url: String, shared_inbox_url: Option<String>, public_key: String, last_fetched_at: DateTime<Utc> }
+        struct Row {
+            url: String,
+            handle: String,
+            display_name: Option<String>,
+            inbox_url: String,
+            shared_inbox_url: Option<String>,
+            public_key: String,
+            last_fetched_at: DateTime<Utc>,
+        }
         sqlx::query_as::<_, Row>(
             "SELECT url,handle,display_name,inbox_url,shared_inbox_url,public_key,last_fetched_at FROM remote_actors WHERE url=$1"
         ).bind(url).fetch_optional(&self.pool).await