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/chat.dart

@@ -204,6 +204,8 @@ class ChatController extends State<ChatPageWithRoom>
 
   bool showEmojiPicker = false;
 
+  bool showAttachmentPicker = false;
+
   String? get threadLastEventId {
     final threadId = activeThreadId;
     if (threadId == null) return null;
@@ -978,18 +980,40 @@ class ChatController extends State<ChatPageWithRoom>
     setState(() => showEmojiPicker = false);
   }
 
+  void hideAttachmentPicker() {
+    setState(() => showAttachmentPicker = false);
+  }
+
   void emojiPickerAction() {
     if (showEmojiPicker) {
       inputFocus.requestFocus();
     } else {
       inputFocus.unfocus();
     }
-    setState(() => showEmojiPicker = !showEmojiPicker);
+    setState(() {
+      showEmojiPicker = !showEmojiPicker;
+      showAttachmentPicker = false;
+    });
+  }
+
+  void attachmentPickerAction() {
+    if (showAttachmentPicker) {
+      inputFocus.requestFocus();
+    } else {
+      inputFocus.unfocus();
+    }
+    setState(() {
+      showAttachmentPicker = !showAttachmentPicker;
+      showEmojiPicker = false;
+    });
   }
 
   void _inputFocusListener() {
-    if (showEmojiPicker && inputFocus.hasFocus) {
-      setState(() => showEmojiPicker = false);
+    if ((showEmojiPicker || showAttachmentPicker) && inputFocus.hasFocus) {
+      setState(() {
+        showEmojiPicker = false;
+        showAttachmentPicker = false;
+      });
     }
   }
 
@@ -1016,6 +1040,7 @@ class ChatController extends State<ChatPageWithRoom>
     Clipboard.setData(ClipboardData(text: _getSelectedEventString()));
     setState(() {
       showEmojiPicker = false;
+      showAttachmentPicker = false;
       selectedEvents.clear();
     });
   }
@@ -1044,6 +1069,7 @@ class ChatController extends State<ChatPageWithRoom>
     if (!mounted) return;
     setState(() {
       showEmojiPicker = false;
+      showAttachmentPicker = false;
       selectedEvents.clear();
     });
     scaffoldMessenger.showSnackBar(
@@ -1120,6 +1146,7 @@ class ChatController extends State<ChatPageWithRoom>
     );
     setState(() {
       showEmojiPicker = false;
+      showAttachmentPicker = false;
       selectedEvents.clear();
     });
   }
@@ -1305,6 +1332,7 @@ class ChatController extends State<ChatPageWithRoom>
   void clearSelectedEvents() => setState(() {
     selectedEvents.clear();
     showEmojiPicker = false;
+    showAttachmentPicker = false;
   });
 
   void clearSingleSelectedEvent() {