Add room preview dialog

Closes #79

lib/helpers/extensions/focus_room.dart

@@ -0,0 +1,36 @@
+import "package:collection/collection.dart";
+import "package:flutter_riverpod/experimental/mutation.dart";
+import "package:nexus/controllers/key.dart";
+import "package:nexus/controllers/spaces.dart";
+import "package:nexus/models/space.dart";
+
+extension FocusRoom on MutationTarget {
+  Future<void> focusRoom(String id) async {
+    final spaces = container.read(SpacesController.provider);
+
+    if (spaces.firstWhereOrNull((space) => space.id == id) case Space _?) {
+      return await container
+          .read(KeyController.provider(KeyController.spaceKey).notifier)
+          .set(id);
+    }
+
+    final parent = spaces.firstWhereOrNull(
+      (space) =>
+          space.children.any((room) => room.metadata?.id == id) ||
+          space.subSpaces.any(
+            (sub) =>
+                sub.room.metadata?.id == id ||
+                sub.children.any((room) => room.metadata?.id == id),
+          ),
+    );
+    if (parent == null) return;
+
+    await container
+        .read(KeyController.provider(KeyController.spaceKey).notifier)
+        .set(parent.id);
+
+    await container
+        .read(KeyController.provider(KeyController.roomKey).notifier)
+        .set(id);
+  }
+}