Add daily cron to run meeting discovery once

[AndreRobitaille]

Set up a daily cron to enqueue the daily scrape and ensure it is the only automated hit to two-rivers.org.

Context

• Run once per day at 23:00 UTC (5pm CST / 6pm CDT).
• Use system cron or Kamal recurring task (not a background loop).

Acceptance criteria

• Add a dedicated entry point (rake task or runner command) that enqueues Scrapers::DiscoverMeetingsJob with a reasonable cutoff window (e.g., since: 90 days ago).
• Daily cron configured to run that entry point at 23:00 UTC.
• No other scheduled/recurring jobs or timers hitting two-rivers.org outside the cron trigger.
• Document the schedule and command in README or ops notes.

Notes

• The discover job should be idempotent; it already upserts by meeting detail URL.
• Daily run should be the only automatic scrape to respect the site.

[AndreRobitaille]

Implemented. Two changes:

1. config/recurring.yml — Added daily_meeting_discovery entry: runs Scrapers::DiscoverMeetingsJob daily at 11pm (23:00 UTC).
2. DiscoverMeetingsJob — Added DEFAULT_LOOKBACK = 90.days so the job defaults to a 90-day window when called without arguments. The since: param still works for manual runs with custom ranges.

No other scheduled/recurring jobs hit two-rivers.org. The discover job is idempotent (upserts by detail_page_url).