feat: remove unused client mutex

- remove unused Mutex from `models.Client` struct
- remove lock from `HandleConnection()`
- replace websocket.Conn with models.Client in `handleClientCommands()`

🤖

internal/websocket/client_commands.go

@@ -3,7 +3,6 @@ package websocket
 import (
 	"encoding/json"
 	"github.com/charmbracelet/log"
-	"github.com/gorilla/websocket"
 
 	"git.smsvc.net/pomodoro/GoTomato/internal/pomodoro"
 	"git.smsvc.net/pomodoro/GoTomato/internal/shared"
@@ -11,7 +10,8 @@ import (
 )
 
 // Listens for commands from a client and handles them
-func handleClientCommands(ws *websocket.Conn) {
+func handleClientCommands(c models.Client) {
+	ws := c.Conn
 	for {
 		var clientCommand models.ClientCommand