Adds a React admin panel (panel/) with Discord OAuth2 login,
live dashboard via WebSocket, and settings/management pages.
Includes Docker build support, Vite proxy config for dev,
game_settings migration, and open-redirect protection on auth callback.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Store guild-specific settings (roles, channels, moderation options) in
database instead of config file, enabling per-guild configuration and
runtime updates without redeployment.
