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/nats/src/lib.rs

@@ -10,7 +10,9 @@ pub struct NatsTransport {
 }
 
 impl NatsTransport {
-    pub fn new(client: async_nats::Client) -> Self { Self { client } }
+    pub fn new(client: async_nats::Client) -> Self {
+        Self { client }
+    }
 }
 
 #[async_trait]
@@ -30,7 +32,9 @@ pub struct NatsMessageSource {
 }
 
 impl NatsMessageSource {
-    pub fn new(client: async_nats::Client) -> Self { Self { client } }
+    pub fn new(client: async_nats::Client) -> Self {
+        Self { client }
+    }
 }
 
 impl MessageSource for NatsMessageSource {
@@ -61,7 +65,10 @@ impl MessageSource for NatsMessageSource {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use domain::{events::DomainEvent, value_objects::{LikeId, ThoughtId, UserId}};
+    use domain::{
+        events::DomainEvent,
+        value_objects::{LikeId, ThoughtId, UserId},
+    };
     use event_payload::EventPayload;
 
     #[test]
@@ -86,7 +93,12 @@ mod tests {
         };
         let payload = EventPayload::from(&event);
         let back = DomainEvent::try_from(payload).unwrap();
-        if let DomainEvent::LikeAdded { user_id, thought_id, .. } = back {
+        if let DomainEvent::LikeAdded {
+            user_id,
+            thought_id,
+            ..
+        } = back
+        {
             assert_eq!(user_id, uid);
             assert_eq!(thought_id, tid);
         } else {