HELD: Staff map: boot SeatLayerView with a manage grant

[pietechsolution]

HELD. Do not merge or publish. This waits for a SeatLayer renderer release that advertises staff-map-v1. That release is pinned in a separate change; until then the load fails cleanly with SeatLayerError.incompatible.

Staff map

A new mode of SeatLayerView for apps used by an organizer's own staff, such as a box office. Boot the view with an event-scoped manage grant (mse_…) instead of buyer access, and it shows the organizer's live board. Staff pick seats (held and sold seats included), the selection arrives on onSelectionChanged, and no hold is placed.

API

// Configuration
SeatLayerConfiguration(
  event: 'ev_xxx',
  manageAccessToken: ManageAccessToken(token: 'mse_…', expiresAt: 1790000000000), // optional
  manageAccessTokenProvider: (ManageAccessRequestContext context) async => ManageAccessToken(...), // renews; also mints when no token
);

// Controller (staff map)
Stream<List<SelectedSeat>> onSelectionChanged;           // the picked seats
Stream<GAArea> onGAClick;                                 // a standing area was tapped
Stream<StaffConnectionState> onStaffConnectionChanged;    // live / reconnecting / ended
Future<bool> focusSection(String? label);                 // null frames the whole venue
Future<void> setUnavailableObjects(List<String> objects, {String? reason});
Future<void> setCategoryPrices(Map<String, StaffCategoryPrice>? prices);
// plus selectObjects, deselectObjects, clearSelection, getSelection, zoomToFit

New types: ManageAccessToken, ManageAccessTokenProvider, ManageAccessRequestContext, ManageAccessRefreshReason (initial, refresh), StaffConnectionState, StaffCategoryPrice, seatLayerStaffMapCapability.

Rules

• The grant is minted for one event with the event:view capability and seatLayerMobileOrigin (https://cdn.seatlayer.io) as its allowed origin.
• A token that is not mse_…, or a grant combined with publicKey, buyerAccessToken or buyerAccessTokenProvider, throws an ArgumentError from the configuration.
• The handshake requires staff-map-v1; without it the load fails with SeatLayerError.incompatible.
• SeatLayerPicker refuses a manage grant with bad_payload.
• Renewals go through the existing access.token.request round trip. A provider failure, or anything that is not an mse_ grant, answers access.token.unavailable and never puts a token in an event.
• semanticallyEquals covers the new fields, so a rebuilt configuration does not reload the map.

Changes

• lib/src/staff_map.dart (new) and its export from lib/seatlayer.dart.
• lib/src/seat_layer_configuration.dart: fields, validation, init payload, equality.
• lib/src/seat_layer_controller.dart: capability gate, grant renewal, staff.connection, three commands.
• test/staff_map_test.dart (new, 12 tests).
• README section and an Unreleased changelog entry.

Checks

• flutter analyze: no issues.
• flutter test test/staff_map_test.dart test/bridge_profile_test.dart test/ready_timing_test.dart test/file_size_test.dart test/payloads_test.dart test/bridge_client_test.dart test/negotiation_test.dart test/seat_layer_view_reload_test.dart: 73/73.
• flutter test test/staff_map_test.dart test/file_size_test.dart test/package_version_test.dart: 14/14, run after the docs change.