wh_messages now holds every message with a channel (all, team, pm, staff,
to_staff, css_say/asay/psay/csay/hsay/cssay) and NULL sender columns for
the console. Seen by a catch-all listener added in Load, which CSS runs
before CS2-SimpleAdmin's (added in OnAllPluginsLoaded), so gagged lines and
@ chat are kept before SimpleAdmin stops or rewrites them. Replaces
001_CreateTables in place: drop wh_messages and wh_migrations first.