Pi: WiFi hotspot (AP on wlan0, 10.42.0.1) + hotspot/wifi toggle scripts + README

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

scripts/hotspot-on.sh

@@ -0,0 +1,5 @@
+#!/usr/bin/env bash
+# Attiva l'access point del Pi su wlan0 (SSID "DJVisualizer").
+# Il telefono si collega alla rete del Pi e apre http://10.42.0.1:8080/
+sudo nmcli connection up Hotspot
+echo "Hotspot attivo. WiFi: DJVisualizer  ·  Remote: http://10.42.0.1:8080/"