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/get_capabilities/get_capabilities_response.g.dart

@@ -8,13 +8,28 @@ part of 'get_capabilities_response.dart';
 
 CapabilitiesResponse _$CapabilitiesResponseFromJson(
   Map<String, dynamic> json,
-) => CapabilitiesResponse(
-  viewForeignTimetables: json['viewForeignTimetables'] as bool? ?? false,
-  pushNotifications: json['pushNotifications'] as bool? ?? false,
-  timetablePastDays: (json['timetablePastDays'] as num?)?.toInt(),
-  timetableFutureDays: (json['timetableFutureDays'] as num?)?.toInt(),
-  userType: json['userType'] as String?,
-);
+) => $checkedCreate('CapabilitiesResponse', json, ($checkedConvert) {
+  final val = CapabilitiesResponse(
+    viewForeignTimetables: $checkedConvert(
+      'viewForeignTimetables',
+      (v) => v as bool? ?? false,
+    ),
+    pushNotifications: $checkedConvert(
+      'pushNotifications',
+      (v) => v as bool? ?? false,
+    ),
+    timetablePastDays: $checkedConvert(
+      'timetablePastDays',
+      (v) => (v as num?)?.toInt(),
+    ),
+    timetableFutureDays: $checkedConvert(
+      'timetableFutureDays',
+      (v) => (v as num?)?.toInt(),
+    ),
+    userType: $checkedConvert('userType', (v) => v as String?),
+  );
+  return val;
+});
 
 Map<String, dynamic> _$CapabilitiesResponseToJson(
   CapabilitiesResponse instance,