GSP Windows Agent Panel Integration

Workspace reference: GSP-WORKSPACE.md

The Panel is authoritative. The Windows agent executes the work the Panel requests.

Integration points

shared key and RPC configuration live in OGP64/OGP/Cfg/Config.pm
startup preferences live in OGP64/OGP/Cfg/bash_prefs.cfg
the Panel talks to the same command surface as the Linux agent wherever practical
game server readiness is reported through the existing server_status RPC, extended with expected/listening/missing port details

The Windows agent should mirror the Linux agent behaviorally as much as possible so the Panel can treat both platforms as one product family.

The dedicated Panel steam_workshop module still uses the legacy steam_workshop XML-RPC call.

Current compatibility rule:

if the Panel sends a blank config_file_path, the Windows agent runs post-install logic only
the generated script must skip all cat / regex / config-write logic in that case
WorkshopModsInfo is still written so the Panel can list/uninstall installed items even when no game config file is edited
new installs write per-home records under WorkshopModsInfo/home_<home_id>/
each record stores mod string, Workshop item ID, title, installed folder/path, Workshop App ID, install status, and timestamps
the generated job writes <game_home>/WorkshopInstallStatus.json as running, completed, or failed
the generated job prints GSP_WORKSHOP_INSTALL_COMPLETE or GSP_WORKSHOP_INSTALL_FAILED so the Panel can avoid stale Update in progress displays if the generic update screen lingers

The Panel remains the source of truth for assigned ports. The Windows agent validates only the ports supplied by the Panel for a specific server.

Detailed design: