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

character-service/src/character_db_client.rs

@@ -1,9 +1,8 @@
-use crate::database::character_db_service_client::CharacterDbServiceClient;
 use crate::database::{
-    Character, CharacterListRequest, CharacterListResponse, CharacterRequest,
-    CreateCharacterRequest, CreateCharacterResponse, DeleteCharacterRequest,
-    DeleteCharacterResponse,
+    character_db_service_client::CharacterDbServiceClient, Character, CharacterListRequest, CharacterListResponse,
+    CharacterRequest, CreateCharacterRequest, CreateCharacterResponse, DeleteCharacterRequest, DeleteCharacterResponse,
 };
+
 use serde::{Deserialize, Serialize};
 use tonic::transport::Channel;