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/src/handlers/world.rs

@@ -1,4 +1,4 @@
-use crate::character_client::CharacterClient;
+use crate::character_client::CharacterClient;
 use crate::connection_service::ConnectionService;
 use crate::packet::{send_packet, Packet, PacketPayload};
 use crate::packet_type::PacketType;
@@ -32,24 +32,14 @@ pub(crate) async fn handle_change_map_req(
     let session_id;
     if let Some(mut state) = connection_service.get_connection(&connection_id) {
         user_id = state.user_id.expect("Missing user id in connection state");
-        session_id = state
-            .session_id
-            .expect("Missing session id in connection state");
-        char_id = state
-            .character_id
-            .expect("Missing character id in connection state");
-        character_id_list = state
-            .character_list
-            .clone()
-            .expect("Missing character id list");
+        session_id = state.session_id.expect("Missing session id in connection state");
+        char_id = state.character_id.expect("Missing character id in connection state");
+        character_id_list = state.character_list.clone().expect("Missing character id list");
     }
 
     let mut character_client = character_client.lock().await;
     let character_data = character_client
-        .get_character(
-            &user_id.to_string(),
-            character_id_list[char_id as usize] as u8,
-        )
+        .get_character(&user_id.to_string(), character_id_list[char_id as usize] as u8)
         .await?;
 
     let character = character_data.character.unwrap_or_default();
@@ -93,24 +83,14 @@ pub(crate) async fn handle_mouse_cmd_req(
     let mut char_id = 0;
     let mut character_id_list: Vec<u32> = Vec::new();
     if let Some(mut state) = connection_service.get_connection(&connection_id) {
-        char_id = state
-            .character_id
-            .expect("Missing character id in connection state");
-        character_id_list = state
-            .character_list
-            .clone()
-            .expect("Missing character id list");
+        char_id = state.character_id.expect("Missing character id in connection state");
+        character_id_list = state.character_list.clone().expect("Missing character id list");
     }
 
     let data = SrvMouseCmd {
         id: character_id_list[char_id as usize] as u16,
         target_id: request.target_id,
-        distance: distance(
-            520000 as f64,
-            520000 as f64,
-            request.x as f64,
-            request.y as f64,
-        ),
+        distance: distance(520000 as f64, 520000 as f64, request.x as f64, request.y as f64),
         x: request.x,
         y: request.y,
         z: request.z,