Show full OpenVPN RW in the UI connection history from stored logs instead of RAM

[cotosso]

Description:
Currently, the UI displays the OpenVPN Roadwarrior connection history only since the last firewall reboot. This happens because the data is read from memory (RAM), which is cleared at each restart.

Why / Purpose
Administrators need visibility on the complete connection history to audit remote access and troubleshoot VPN usage over time, regardless of system uptime. Limiting the view to the current session hinders analysis and reporting.

Proposed solution
Read the OpenVPN connection history from the persistent logs stored in the system storage (/mnt/data/openvpn/ns_roadwarrior1/connections.db) instead of relying only on data kept in RAM. This would allow the UI to show all past connections, not just those after the last reboot.