docs: cross-reference leaderboard duplication, service-role-key warning

- Add cross-reference comments between dashboard-queries.ts computeLeaderboard()
  and dashboard/ui.ts renderLeaderboard() so maintainers know to update both
- Add security note in setup-team-dashboard about service-role-key visibility
  in pg_cron job table

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

supabase/functions/dashboard/ui.ts

@@ -768,6 +768,8 @@ export function getDashboardHTML(supabaseUrl: string, anonKey: string): string {
   }
 
   // ---- Leaderboard ----
+  // NOTE: This leaderboard aggregation mirrors lib/dashboard-queries.ts computeLeaderboard().
+  // If you change the logic here, update the shared pure function too (used by CLI).
   function renderLeaderboard() {
     const ws = weekStart();
     const hasAnyData = data.evalRuns || data.shipLogs || data.transcripts;