add room directory support

lib/helpers/extensions/get_localpart.dart

@@ -4,6 +4,12 @@ extension GetLocalpart on String {
   /// Whether this looks like a valid Matrix user ID, e.g. `@user:example.com`.
   bool get isValidUserId => RegExp(r"^@[^:\s]+:[^\s]+$").hasMatch(this);
 
+  /// Whether this is a valid Matrix server name, e.g. `example.com:8448`.
+  bool get isValidServerName => RegExp(
+    r"^(\[[0-9a-f:.]+\]|[a-z0-9.-]{1,255})(:\d{1,5})?$",
+    caseSensitive: false,
+  ).hasMatch(this);
+
   String? get serverName {
     final index = indexOf(":");
     return index == -1 ? null : substring(index + 1);

lib/helpers/extensions/join_room.dart

@@ -17,6 +17,7 @@ extension JoinRoom on BuildContext {
   }) async {
     final container = ProviderScope.containerOf(this);
     final messenger = ScaffoldMessenger.of(this);
+    final navigator = Navigator.of(this);
 
     final roomId = await withProgressSnackbar(
       "Joining $name...",
@@ -31,6 +32,7 @@ extension JoinRoom on BuildContext {
         action: .new(
           label: "Open",
           onPressed: () async {
+            navigator.popUntil((route) => route.isFirst);
             await container.focusRoom(roomId);
             container.read(SidebarPageController.provider.notifier).set(.rooms);
           },

lib/helpers/extensions/room_summary_display.dart

@@ -0,0 +1,18 @@
+import "package:material_ui/material_ui.dart";
+import "package:nexus/models/content/create.dart";
+import "package:nexus/models/room_summary.dart";
+
+extension RoomSummaryDisplay on RoomSummary {
+  bool get isSpace => roomType == RoomType.space;
+
+  IconData get icon => isSpace ? Icons.workspaces : Icons.numbers;
+
+  String get displayName =>
+      name ?? canonicalAlias ?? (isSpace ? "Unnamed Space" : "Unnamed Room");
+
+  /// E.g. "Space · 12 members"
+  String get details => [
+    if (isSpace) "Space",
+    if (joinedMembers case final members?) "$members members",
+  ].join(" · ");
+}