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/pages/chat_list/tabs/channels_tab.dart

@@ -95,6 +95,8 @@ class _ChannelsTabState extends State<ChannelsTab> {
                         room,
                         key: Key('channel_list_item_${room.id}'),
                         onTap: () => widget.controller.onChatTap(room),
+                        onLongPress: (context) =>
+                            widget.controller.chatContextAction(room, context),
                         activeChat: widget.controller.activeChat == room.id,
                       );
                     },

lib/pages/chat_list/tabs/murals_tab.dart

@@ -101,6 +101,8 @@ class _MuralsTabState extends State<MuralsTab> {
                         room,
                         key: Key('mural_list_item_${room.id}'),
                         onTap: () => widget.controller.onChatTap(room),
+                        onLongPress: (context) =>
+                            widget.controller.chatContextAction(room, context),
                         activeChat: widget.controller.activeChat == room.id,
                         displayAvatar: Uri.tryParse(
                           creatorState?.content.tryGet<String>('avatar_url') ??