hardened API decoding against server fields the models did not expect

The Talk room list crashed for a new account because the server omits
lastMessage for rooms without a visible message and the model required it.
Beyond that single field, a review of the Talk models against the OpenAPI
spec of the installed version (23.0.8) found the same crash class in several
places: closed enums over open server values (inCall bitmask, rich-object
types, actor and message types), a deleted parent sent as {id, deleted},
and the autocomplete status arriving as an object.

- json_serializable `checked: true`: decode errors now name class and field
- lists (rooms, messages, participants, autocomplete) decode per entry;
  a malformed entry is skipped and reported via ClientErrorReporter
- unknownEnumValue fallbacks for all response enums of Talk and breakers
- lastMessage nullable; inCall as bitmask; deleted parent placeholder;
  autocomplete status object/string; fixed shareWithDisplayNameUnique key
- GetRoomParams no longer sends null query parameters

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HrepDTL4qDe35TuS29sLW3

lib/api/marianumconnect/queries/absence/absence_prefill_response.g.dart

@@ -8,12 +8,15 @@ part of 'absence_prefill_response.dart';
 
 AbsencePrefillResponse _$AbsencePrefillResponseFromJson(
   Map<String, dynamic> json,
-) => AbsencePrefillResponse(
-  firstName: json['firstName'] as String? ?? '',
-  lastName: json['lastName'] as String? ?? '',
-  className: json['className'] as String? ?? '',
-  phone: json['phone'] as String? ?? '',
-);
+) => $checkedCreate('AbsencePrefillResponse', json, ($checkedConvert) {
+  final val = AbsencePrefillResponse(
+    firstName: $checkedConvert('firstName', (v) => v as String? ?? ''),
+    lastName: $checkedConvert('lastName', (v) => v as String? ?? ''),
+    className: $checkedConvert('className', (v) => v as String? ?? ''),
+    phone: $checkedConvert('phone', (v) => v as String? ?? ''),
+  );
+  return val;
+});
 
 Map<String, dynamic> _$AbsencePrefillResponseToJson(
   AbsencePrefillResponse instance,