feat(schedule): support KOL subscription targets and random time windows

Extend schedule tasks to dispatch KOL subscription prompts in addition
to prompt rules, add daily/weekly scheduling with fixed or random time
windows, and track dispatch outcomes (last run, status, consecutive
failures).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.gitignore

@@ -3,6 +3,7 @@ node_modules/
 .pnpm-store/
 coverage/
 dist/
+output/
 .env
 .env.local
 .env.signing