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

packet-service/Cargo.toml

@@ -3,6 +3,15 @@ name = "packet-service"
 version = "0.1.0"
 edition = "2021"
 
+# Define both a binary and a library target
+[[bin]]
+name = "packet-service"
+path = "src/main.rs"
+
+[lib]
+name = "packet_service"
+path = "src/lib.rs"
+
 [features]
 mocks = []
 consul = []