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/json_lenient.dart

@@ -0,0 +1,46 @@
+import 'package:json_annotation/json_annotation.dart';
+
+/// Decodes server lists element by element so one entry the model cannot map
+/// (a field the server dropped, an enum value it added) is skipped and
+/// recorded instead of failing the whole response and with it the screen.
+///
+/// Skipped entries are collected per isolate; the API layer drains them with
+/// [drainDecodeWarnings] and reports them, so a drift in the server's format
+/// still reaches us without taking the feature down for the user.
+final List<String> _warnings = [];
+
+List<T> decodeListLenient<T>(
+  Object? raw,
+  T Function(Map<String, dynamic>) fromJson, {
+  required String what,
+}) {
+  final items = <T>[];
+  if (raw is! List<dynamic>) {
+    throw FormatException(
+      'expected a list of ${what}s, got ${raw.runtimeType}',
+    );
+  }
+  for (final entry in raw) {
+    try {
+      items.add(fromJson(entry as Map<String, dynamic>));
+    } on CheckedFromJsonException catch (e) {
+      _warnings.add('$what: $e');
+    } on TypeError catch (e) {
+      _warnings.add('$what: $e');
+    }
+  }
+  return items;
+}
+
+Set<T> decodeSetLenient<T>(
+  Object? raw,
+  T Function(Map<String, dynamic>) fromJson, {
+  required String what,
+}) => decodeListLenient(raw, fromJson, what: what).toSet();
+
+/// Returns and clears the entries skipped since the last call.
+List<String> drainDecodeWarnings() {
+  final out = List<String>.of(_warnings);
+  _warnings.clear();
+  return out;
+}