- Restructure hierarchy: Month → Event → Expense (new months table, FK)
- Add MonthHandler with CRUD, monthly reports, dropdown create form
- Events now scoped under months with extended ownership chain
- AI extraction: 16 specific expense categories (Airfare, Meals, etc.)
- UI: category dropdown, button-consistent cards, centered mobile shell on desktop
- Dashboard/month views show claim totals per card
- Description field now mandatory, forms simplified
- Months sorted by name chronologically (latest first)
- Email now includes both report (CSV/PDF) + ZIP of all receipt images
- ZIP images named {event-name}-{index}.{ext} matching list order
- Uses Go's archive/zip (stdlib, no external deps)
- Sender.SendReport now accepts []*Attachment for multiple files
- Gracefully skips missing image files with warnings
