Applicatie afmaken en GUI-flow herstellen

Voegt boodschappenlijsten, productbeheer, realtime synchronisatie en browsercache-updates toe. Herstelt login- en sessiegedrag en maakt database-seeding herhaalbaar.\n\nCo-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

app.js

@@ -1,12 +1,20 @@
 require("dotenv").config();
 
 const http = require("http");
+const { Server } = require("socket.io");
 
 const createApp = require("./config/express");
+const session = require("./config/session");
+const socketHandlers = require("./sockets/handlers");
 
 const app = createApp();
 
 const server = http.createServer(app);
+const io = new Server(server);
+
+io.use((socket, next) => session(socket.request, {}, next));
+socketHandlers(io);
+app.locals.io = io;
 
 const PORT = process.env.PORT || 3000;