feat(server): restructure Pomodoro server into modular components

- move server logic to cmd/server/main.go
- create packages for websocket, pomodoro and broadcast handling
- define models for messages
- remove old GoTomato.go file
- update README

🤖

internal/broadcast/broadcast.go

@@ -0,0 +1,28 @@
+package broadcast
+
+import (
+	"encoding/json"
+	"git.smsvc.net/pomodoro/GoTomato/pkg/models"
+	"github.com/gorilla/websocket"
+	"log"
+)
+
+// BroadcastMessage sends a message to all connected WebSocket clients.
+func BroadcastMessage(clients map[*websocket.Conn]bool, message models.BroadcastMessage) {
+	// Marshal the message into JSON format
+	jsonMessage, err := json.Marshal(message)
+	if err != nil {
+		log.Printf("Error marshalling message: %v", err)
+		return
+	}
+
+	// Iterate over all connected clients and broadcast the message
+	for client := range clients {
+		err := client.WriteMessage(websocket.TextMessage, jsonMessage)
+		if err != nil {
+			log.Printf("Error broadcasting to client: %v", err)
+			client.Close()
+			delete(clients, client) // Remove the client if an error occurs
+		}
+	}
+}