Database:
- Add slug, roaster_slug, brew_data_json columns to timeline_events
- Migration backfills existing data from related tables
- Remove 9-way LEFT JOIN from list query, read directly from columns
Frontend:
- Use CSS :nth-of-type(odd/even) for alternating timeline layout
- Remove JavaScript class manipulation when appending month events
- Simplify infinite scroll month-merging logic
This eliminates query-time JOINs across 5 tables and ~20 lines of
client-side JavaScript for pattern maintenance.
