CUB-231: Mosquitto MQTT broker setup on Pi Zero 2 W hub

- Install script for Mosquitto MQTT broker on Pi Zero 2 W (10.60.1.101)
- Persistence enabled with data stored in /var/lib/mosquitto/data/
- Topic ACL configuration for hub, sensor, mobile, and admin users
- systemd service with security hardening (NoNewPrivileges, ProtectSystem)
- Configuration files: mosquitto.conf, acl.conf
- Validation script to verify setup before deployment

.gitignore

@@ -0,0 +1,33 @@
+# .gitignore for Mosquitto Hub Config
+
+# Don't commit sensitive files
+/etc/mosquitto/passwd
+*.pem
+*.key
+*.crt
+
+# Generated files
+*.log
+*.bak
+*~
+
+# IDE
+.idea/
+.vscode/
+*.swp
+*.swo
+*~
+
+# OS
+.DS_Store
+Thumbs.db
+
+# Temporary files
+/tmp/
+/var/tmp/
+*.tmp
+
+# Python
+__pycache__/
+*.py[cod]
+*$py.class