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/README.md

@@ -0,0 +1,93 @@
+# Character Service
+
+The Character Service manages character creation, deletion, and retrieval in the MMORPG server architecture.
+
+## Overview
+
+The Character Service provides gRPC endpoints for:
+- Retrieving character lists for users
+- Creating new characters
+- Deleting characters
+- Retrieving detailed character information
+
+It communicates with the database service to store and retrieve character data.
+
+## Architecture
+
+The service is built using the following components:
+
+- **gRPC Server**: Exposes character management endpoints
+- **Character DB Client**: Communicates with the database service for character data
+
+## Service Endpoints
+
+The Character Service exposes the following gRPC endpoints:
+
+### GetCharacterList
+Retrieves a list of characters for a user.
+
+```protobuf
+rpc GetCharacterList(GetCharacterListRequest) returns (GetCharacterListResponse);
+```
+
+### CreateCharacter
+Creates a new character for a user.
+
+```protobuf
+rpc CreateCharacter(CreateCharacterRequest) returns (CreateCharacterResponse);
+```
+
+### DeleteCharacter
+Marks a character for deletion or permanently deletes it.
+
+```protobuf
+rpc DeleteCharacter(DeleteCharacterRequest) returns (DeleteCharacterResponse);
+```
+
+### GetCharacter
+Retrieves detailed information about a specific character.
+
+```protobuf
+rpc GetCharacter(GetCharacterRequest) returns (GetCharacterResponse);
+```
+
+## Character Data Structure
+
+Characters in the system have the following key attributes:
+
+- **Basic Information**: ID, name, user ID, creation/deletion dates
+- **Appearance**: Race, face, hair, stone
+- **Stats**: Level, attributes (STR, DEX, INT, etc.), HP, MP, experience
+- **Inventory**: Items, equipment
+- **Position**: Map ID, coordinates
+
+## Configuration
+
+The service can be configured using environment variables:
+
+- `LISTEN_ADDR`: The address to listen on (default: "0.0.0.0")
+- `SERVICE_PORT`: The port to listen on (default: "50053")
+- `LOG_LEVEL`: Logging level (default: "info")
+
+## Running the Service
+
+### Local Development
+
+```bash
+cargo run
+```
+
+### Docker
+
+```bash
+docker build -t character-service .
+docker run -p 50053:50053 character-service
+```
+
+## Integration with External Systems
+
+The Character Service integrates with:
+
+- **Database Service**: For character data storage and retrieval
+- **Auth Service**: For user authentication and authorization
+- **Packet Service**: For handling client requests related to characters