Adds trips table usage across API and UI: trip CRUD, per-trip analytics
(category/daily/merchant/tag/participant breakdowns), tag-to-trip
conversion, trip assignment via transaction overrides, and trip filter
in the transactions view. Recovered from working tree after local git
corruption; feature was already live via host-context Docker builds.
- tags table: name, color; transaction_tags junction table
- GET/POST /api/tags; DELETE /api/tags/:id
- POST/DELETE /api/transactions/:id/tags for per-transaction tagging
- Bulk tag/untag via /api/transactions/bulk (action: tag/untag)
- Tags returned inline with transaction list via LATERAL join
- Tag filter on Transactions page
- Bulk "Tag as..." in bulk action bar
- Tag pills + "+" picker on each transaction row
- /tags page: create with color picker, list with counts, delete