Skip past days with existing files, verify admin via delivery_email
monopam:
- Make --aggregate the default for daily changes (add --no-aggregate to skip)
- Skip past days entirely if per-day file exists to avoid redundant Claude calls
- For today, still check if entry exists before regenerating
- Simplify Zulip format headers ("Updates for..." instead of "## Changes for...")
poe:
- Fix admin verification to use delivery_email from Zulip API
- Fallback to sender_email if API call fails
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>