feat: add REST + Socket.IO fallback for Python server

Add RestSocketAdapter that uses:
- REST API for actions (login, logout, terminals)
- Socket.IO for real-time events (IpbxEvent)

ConnectionManager now tries SignalR first (.NET server),
then falls back to REST+SocketIO (Python server).

This enables the client to work with both servers during migration.

main.js

@@ -317,7 +317,8 @@ async function startSignalRConnection() {
     console.log(`Connexion établie via ${connectionInfo.type}`);
     logSignalR(`✅ Connexion établie avec succès (${connectionInfo.type})`, {
       connectionType: connectionInfo.type,
-      isWebSocketFallback: connectionInfo.isWebSocketFallback,
+      isSignalR: connectionInfo.isSignalR,
+      isRestSocketIO: connectionInfo.isRestSocketIO,
       status: 'connected',
       serverUrl: connectionInfo.serverUrl
     });