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/block.rs

@@ -1,9 +1,17 @@
 use async_trait::async_trait;
+use domain::{
+    errors::DomainError, models::social::Block, ports::BlockRepository, value_objects::UserId,
+};
 use sqlx::PgPool;
-use domain::{errors::DomainError, models::social::Block, ports::BlockRepository, value_objects::UserId};
 
-pub struct PgBlockRepository { pool: PgPool }
-impl PgBlockRepository { pub fn new(pool: PgPool) -> Self { Self { pool } } }
+pub struct PgBlockRepository {
+    pool: PgPool,
+}
+impl PgBlockRepository {
+    pub fn new(pool: PgPool) -> Self {
+        Self { pool }
+    }
+}
 
 #[async_trait]
 impl BlockRepository for PgBlockRepository {
@@ -31,14 +39,13 @@ impl BlockRepository for PgBlockRepository {
     }
 
     async fn exists(&self, blocker_id: &UserId, blocked_id: &UserId) -> Result<bool, DomainError> {
-        let count: i64 = sqlx::query_scalar(
-            "SELECT COUNT(*) FROM blocks WHERE blocker_id=$1 AND blocked_id=$2"
-        )
-        .bind(blocker_id.as_uuid())
-        .bind(blocked_id.as_uuid())
-        .fetch_one(&self.pool)
-        .await
-        .map_err(|e| DomainError::Internal(e.to_string()))?;
+        let count: i64 =
+            sqlx::query_scalar("SELECT COUNT(*) FROM blocks WHERE blocker_id=$1 AND blocked_id=$2")
+                .bind(blocker_id.as_uuid())
+                .bind(blocked_id.as_uuid())
+                .fetch_one(&self.pool)
+                .await
+                .map_err(|e| DomainError::Internal(e.to_string()))?;
         Ok(count > 0)
     }
 }
@@ -46,23 +53,33 @@ impl BlockRepository for PgBlockRepository {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use chrono::Utc;
-    use domain::{models::user::User, value_objects::*};
     use crate::user::PgUserRepository;
+    use chrono::Utc;
     use domain::ports::UserRepository;
+    use domain::{models::user::User, value_objects::*};
 
     async fn seed_user(pool: &sqlx::PgPool, username: &str, email: &str) -> User {
         let repo = PgUserRepository::new(pool.clone());
-        let u = User::new_local(UserId::new(), Username::new(username).unwrap(), Email::new(email).unwrap(), PasswordHash("h".into()));
-        repo.save(&u).await.unwrap(); u
+        let u = User::new_local(
+            UserId::new(),
+            Username::new(username).unwrap(),
+            Email::new(email).unwrap(),
+            PasswordHash("h".into()),
+        );
+        repo.save(&u).await.unwrap();
+        u
     }
 
     #[sqlx::test(migrations = "./migrations")]
     async fn block_exists(pool: sqlx::PgPool) {
         let alice = seed_user(&pool, "alice", "alice@ex.com").await;
-        let bob   = seed_user(&pool, "bob",   "bob@ex.com").await;
+        let bob = seed_user(&pool, "bob", "bob@ex.com").await;
         let repo = PgBlockRepository::new(pool);
-        let block = Block { blocker_id: alice.id.clone(), blocked_id: bob.id.clone(), created_at: Utc::now() };
+        let block = Block {
+            blocker_id: alice.id.clone(),
+            blocked_id: bob.id.clone(),
+            created_at: Utc::now(),
+        };
         repo.save(&block).await.unwrap();
         assert!(repo.exists(&alice.id, &bob.id).await.unwrap());
         assert!(!repo.exists(&bob.id, &alice.id).await.unwrap());
@@ -71,9 +88,13 @@ mod tests {
     #[sqlx::test(migrations = "./migrations")]
     async fn unblock(pool: sqlx::PgPool) {
         let alice = seed_user(&pool, "alice", "alice@ex.com").await;
-        let bob   = seed_user(&pool, "bob",   "bob@ex.com").await;
+        let bob = seed_user(&pool, "bob", "bob@ex.com").await;
         let repo = PgBlockRepository::new(pool);
-        let block = Block { blocker_id: alice.id.clone(), blocked_id: bob.id.clone(), created_at: Utc::now() };
+        let block = Block {
+            blocker_id: alice.id.clone(),
+            blocked_id: bob.id.clone(),
+            created_at: Utc::now(),
+        };
         repo.save(&block).await.unwrap();
         repo.delete(&alice.id, &bob.id).await.unwrap();
         assert!(!repo.exists(&alice.id, &bob.id).await.unwrap());