chore: rimuove script e dipendenze inutilizzati in dev

- Rimuove script preview e start (duplicati di serve)
- Rimuove dipendenza concurrently (mai usata)
- Aggiunge persistenza stato al plugin dev WebSocket

vite-plugin-websocket.js

@@ -1,13 +1,14 @@
 import { WebSocketServer } from 'ws'
 import { setupWebSocketHandler } from './src/websocket-handler.js'
 import { printServerInfo } from './src/server-utils.js'
+import { loadState, saveState } from './src/persist.js'
 
 export default function websocketPlugin() {
   return {
     name: 'vite-plugin-websocket',
     configureServer(server) {
       const wss = new WebSocketServer({ noServer: true })
-      setupWebSocketHandler(wss)
+      setupWebSocketHandler(wss, { initialState: loadState(), onStateChange: saveState })
 
       // Rewrite /display → / (index.html) e /controller → /controller.html
       server.middlewares.use((req, _res, next) => {