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

proto/auth.proto

@@ -10,9 +10,6 @@ service AuthService {
   rpc ValidateToken(ValidateTokenRequest) returns (ValidateTokenResponse);
   rpc ValidateSession(ValidateSessionRequest) returns (ValidateSessionResponse);
   rpc RefreshSession(ValidateSessionRequest) returns (RefreshSessionResponse);
-  rpc Register (RegisterRequest) returns (RegisterResponse);
-  rpc RequestPasswordReset (PasswordResetRequest) returns (PasswordResetResponse);
-  rpc ResetPassword (ResetPasswordRequest) returns (ResetPasswordResponse);
 }
 
 message LoginRequest {
@@ -55,30 +52,4 @@ message RefreshSessionResponse {
   bool valid = 1;
 }
 
-message RegisterRequest {
-  string username = 1;
-  string email = 2;
-  string password = 3;
-}
 
-message RegisterResponse {
-  int32 user_id = 1;
-  string message = 2;
-}
-
-message PasswordResetRequest {
-  string email = 1;
-}
-
-message PasswordResetResponse {
-  string message = 1;
-}
-
-message ResetPasswordRequest {
-  string reset_token = 1;
-  string new_password = 2;
-}
-
-message ResetPasswordResponse {
-  string message = 1;
-}