feat: menu de contexto em bottom sheet, painel de anexos, perfil e feed do mural

- Salas (chat, canais, murais e salas de espacos) abrem bottom sheet com grid de acoes
- Botao + da barra de digitacao abre painel de anexos em grid de 3 colunas que empurra a caixa de texto
- Modal do perfil permite editar nome/status e ler QR code (mobile)
- Alterar status atualiza localmente via extensao do SDK matrix
- Mural pre-carrega historico para exibir todas as midias em dispositivos sem cache

lib/utils/matrix_sdk_extensions/client_presence_extension.dart

@@ -0,0 +1,33 @@
+// SPDX-FileCopyrightText: 2019-Present Christian Kußowski
+// SPDX-FileCopyrightText: 2019-Present Contributors to FluffyChat
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+import 'package:matrix/matrix.dart';
+
+extension ClientPresenceExtension on Client {
+  /// Sets the own presence status message.
+  ///
+  /// The SDK's [Client.setPresence] only performs the HTTP request and does not
+  /// update the local presence cache, the database or the
+  /// [Client.onPresenceChanged] stream. As a result
+  /// [Client.fetchCurrentPresence] keeps returning the previous status until the
+  /// homeserver echoes it back over `/sync`. This helper updates all local
+  /// caches after a successful request so the new status is shown immediately.
+  Future<void> setStatusMessage(String statusMsg) async {
+    final userId = userID;
+    if (userId == null) return;
+    await setPresence(userId, PresenceType.online, statusMsg: statusMsg);
+    final presence = CachedPresence(
+      PresenceType.online,
+      null,
+      statusMsg,
+      null,
+      userId,
+    );
+    // ignore: deprecated_member_use
+    presences[userId] = presence;
+    await database.storePresence(userId, presence);
+    onPresenceChanged.add(presence);
+  }
+}