Add comprehensive documentation and unit tests

Documentation:
- Add detailed README files for all services (auth, character, database, launcher, packet, utils, world)
- Create API documentation for the database service with detailed endpoint specifications
- Document database schema and relationships
- Add service architecture overviews and configuration instructions

Unit Tests:
- Implement comprehensive test suite for database repositories (user, character, session)
- Add gRPC service tests for database interactions
- Create tests for packet service components (bufferpool, connection, packets)
- Add utility service tests (health check, logging, load balancer, redis cache, service discovery)
- Implement auth service user tests
- Add character service tests

Code Structure:
- Reorganize test files into a more consistent structure
- Create a dedicated tests crate for integration testing
- Add test helpers and mock implementations for easier testing

auth-service/src/session_client.rs

@@ -1,16 +1,15 @@
-use crate::session::{session_service_client::SessionServiceClient, GetSessionRequest, GetSessionResponse, RefreshSessionRequest, RefreshSessionResponse};
+use crate::session::{
+    session_service_client::SessionServiceClient, GetSessionRequest, GetSessionResponse, RefreshSessionRequest,
+    RefreshSessionResponse,
+};
 use async_trait::async_trait;
-use chrono::{DateTime, Utc};
 use std::error::Error;
 use tonic::transport::Channel;
 
 #[async_trait]
 pub trait SessionClientTrait: Sized {
     async fn connect(endpoint: &str) -> Result<Self, Box<dyn std::error::Error>>;
-    async fn get_session(
-        &mut self,
-        session_id: String,
-    ) -> Result<GetSessionResponse, Box<dyn std::error::Error>>;
+    async fn get_session(&mut self, session_id: String) -> Result<GetSessionResponse, Box<dyn std::error::Error>>;
     async fn refresh_session(
         &mut self,
         session_id: String,
@@ -27,18 +26,14 @@ impl SessionClientTrait for SessionClient {
         let client = SessionServiceClient::connect(endpoint.to_string()).await?;
         Ok(Self { client })
     }
-    
+
     async fn get_session(&mut self, session_id: String) -> Result<GetSessionResponse, Box<dyn Error>> {
-        let request = tonic::Request::new(GetSessionRequest {
-            session_id,
-        });
+        let request = tonic::Request::new(GetSessionRequest { session_id });
         let response = self.client.get_session(request).await?;
         Ok(response.into_inner())
     }
     async fn refresh_session(&mut self, session_id: String) -> Result<RefreshSessionResponse, Box<dyn Error>> {
-        let request = tonic::Request::new(RefreshSessionRequest {
-            session_id,
-        });
+        let request = tonic::Request::new(RefreshSessionRequest { session_id });
         let response = self.client.refresh_session(request).await?;
         Ok(response.into_inner())
     }