feat: Phase 1 complete — Matrix login, rooms, chat, profile

- Direct m.login.password auth against matrix.m8chat.au
- Room list with unread badges, last message, timestamps
- Chat timeline (text, images, files, replies, reactions)
- Profile screen with expandable Notifications and Security sections
- Olm E2EE initialisation (web WASM bootstrap)
- Global error handler preventing Matrix SDK crashes
- GoRouter with refreshListenable (no recreation on auth change)
- Feature-first clean architecture: Riverpod + GoRouter + Drift
- Deployed to https://app2.m8chat.au

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

lib/features/chat/domain/message_model.dart

@@ -0,0 +1,45 @@
+// Version: 1.0.0 | Created: 2026-04-01
+// Immutable message model for the chat timeline.
+
+import 'package:freezed_annotation/freezed_annotation.dart';
+
+part 'message_model.freezed.dart';
+
+/// Content type of a message event.
+enum MessageType {
+  text,
+  image,
+  file,
+  audio,
+  video,
+  sticker,
+  redacted,
+  unsupported,
+}
+
+@freezed
+abstract class MessageModel with _$MessageModel {
+  const factory MessageModel({
+    required String eventId,
+    required String roomId,
+    required String senderId,
+    required String senderDisplayName,
+    String? senderAvatarUrl,
+    required DateTime timestamp,
+    required MessageType type,
+    // Text content (for text messages).
+    String? body,
+    // URL for media messages.
+    String? mediaUrl,
+    // MXC URI for the media (used to download from homeserver).
+    String? mxcUrl,
+    // If this is a reply, the event ID of the original message.
+    String? inReplyToEventId,
+    // Reactions: emoji → list of sender IDs.
+    @Default({}) Map<String, List<String>> reactions,
+    // Read receipts: sender IDs of users who have read up to this event.
+    @Default([]) List<String> readByUserIds,
+    @Default(false) bool isEdited,
+    @Default(false) bool isMine,
+  }) = _MessageModel;
+}