Calculate metrics from first relevant event to now (capped at 30 days)
instead of a fixed 30-day window. This fixes inaccurate metrics for new
users who have only a few days of data.
Changes:
- Add _get_first_event_ts() and _calculate_window() helpers to stats.py
- Add window_days field to EggStats dataclass
- Update routes/eggs.py and routes/feed.py to use dynamic window
- Update templates to display "N-day avg" instead of "30-day avg"
- Use ceiling division for window_days to ensure first event is included
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
