feature: trips


GET /api/trips/by-user ✅

GET /api/trips/by-trip/{trip_id} ✅

GET /api/trips/{trip_id}/summarize ✅

GET /api/trips/recommended ✅

GET /api/trips/invited ✅

POST /api/trips ✅

PATCH /api/trips/{trip_id} ✅

DELETE /api/trips/{trip_id} ✅

DELETE /api/trips/{trip_id}/leave ✅