alter table ems.site
  add column if not exists discord_webhook_daily_url text,
  add column if not exists discord_webhook_error_url text;

comment on column ems.site.discord_webhook_daily_url is
'Discord webhook pro běžné denní zprávy (např. ranní ekonomický report). Per-site konfigurace.';

comment on column ems.site.discord_webhook_error_url is
'Discord webhook pro error/critical alerty (mismatch, fatal plan vs actual, clock verify exhausted, apod.). Per-site konfigurace.';