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/models/mc_holiday.g.dart

@@ -6,12 +6,22 @@ part of 'mc_holiday.dart';
 // JsonSerializableGenerator
 // **************************************************************************
 
-McHoliday _$McHolidayFromJson(Map<String, dynamic> json) => McHoliday(
-  shortName: json['shortName'] as String,
-  longName: json['longName'] as String,
-  startDate: McHoliday._dateFromJson(json['startDate'] as String),
-  endDate: McHoliday._dateFromJson(json['endDate'] as String),
-);
+McHoliday _$McHolidayFromJson(Map<String, dynamic> json) =>
+    $checkedCreate('McHoliday', json, ($checkedConvert) {
+      final val = McHoliday(
+        shortName: $checkedConvert('shortName', (v) => v as String),
+        longName: $checkedConvert('longName', (v) => v as String),
+        startDate: $checkedConvert(
+          'startDate',
+          (v) => McHoliday._dateFromJson(v as String),
+        ),
+        endDate: $checkedConvert(
+          'endDate',
+          (v) => McHoliday._dateFromJson(v as String),
+        ),
+      );
+      return val;
+    });
 
 Map<String, dynamic> _$McHolidayToJson(McHoliday instance) => <String, dynamic>{
   'shortName': instance.shortName,