Add rooms & groups allocation

Supervisors can split an event's named attendees into allocation sets
(rooms, small groups, buses) with capacity, gender and leader per group,
using a drag-and-drop board or auto-allocate (keep bookings together or
split them). Adds printable group and master lists (medical view
audited), the group on tickets and in My Events, messaging by group,
a "My groups" page for leaders, and an optional per-event gender
question for named attendees.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

CHANGELOG.md

@@ -7,6 +7,20 @@ and this project follows [Semantic Versioning](https://semver.org/).
 
 ## [Unreleased]
 
+### Added
+
+- Rooms & groups (Supervisor → Rooms & groups), for camps and lockdowns: put attendees into rooms, cabins, small groups, teams or buses.
+  - Each event can have several allocation sets (e.g. "Rooms" and "Buses"). Each set has groups with an optional capacity, an optional gender restriction and an optional leader (a staff member).
+  - A drag-and-drop board puts people not yet placed on the left and groups, with capacity counters, on the right. Full groups and groups for the other gender won't accept a person.
+  - Auto-allocate fills groups evenly with everyone not yet placed, respecting capacity and gender. It can keep people on the same booking together or spread them out.
+  - Printable lists per group (with leader) and a master list. On youth events they can include medical and emergency details from consent forms; viewing those is recorded in the audit log.
+  - "Show on tickets" prints the group on each person's ticket and shows it in My Events.
+  - Email and WhatsApp attendees can be sent to one group ("Bus 2 leaves at 07:30"). Messages go to whoever booked for the people in it.
+  - Group leaders see their people under Staff → My groups. Medical details are shown to supervisors only.
+- New event setting "Ask each person's gender" (under Named attendees). It adds a gender choice for each named person on the registration page, at the door, on the kiosk, in manual registration and in My Events, and is needed for gender-split rooms.
+- New `/api/allocations` endpoints.
+  - Requires the `add_room_allocation` database migration.
+
 ## [1.18.0] - 2026-10-19
 
 ### Added