fix(galaxy): include undeployed areas in browse + re-root orphaned objects

The hierarchy query returned deployed objects only (deployed_package_id <> 0), so
areas whose containing area is undeployed were orphaned and hidden from /browse —
on wonder, only the lone deployed root area surfaced. Include category-13 Area
objects regardless of deployment, and in GalaxyHierarchyIndex re-root any object
whose parent is absent from the set (e.g. a deleted container area) so nothing
disappears under a phantom parent id.

src/ZB.MOM.WW.MxGateway.Tests/Galaxy/GalaxyHierarchyIndexTests.cs

@@ -75,6 +75,35 @@ public sealed class GalaxyHierarchyIndexTests
         }
     }
 
+    /// <summary>
+    ///     Verifies an object whose parent is absent from the set (e.g. a deleted/undeployed
+    ///     container area) is re-rooted under sentinel 0 rather than vanishing under a phantom
+    ///     parent id that browse never reaches from the root.
+    /// </summary>
+    [Fact]
+    public void ChildrenByParent_OrphanWithMissingParent_AppearsAsRoot()
+    {
+        GalaxyObject realRoot = new() { GobjectId = 1, ParentGobjectId = 0, IsArea = true, ContainedName = "RealRoot" };
+        GalaxyObject orphanArea = new() { GobjectId = 2, ParentGobjectId = 5008, IsArea = true, ContainedName = "Orphan" };
+        GalaxyObject orphanChild = new() { GobjectId = 3, ParentGobjectId = 2, ContainedName = "Child" };
+
+        GalaxyHierarchyIndex index = GalaxyHierarchyIndex.Build([realRoot, orphanArea, orphanChild]);
+
+        // Both the real root and the orphan (its parent 5008 is absent) surface under root.
+        Assert.True(index.ChildrenByParent.TryGetValue(0, out IReadOnlyList<GalaxyObjectView>? roots));
+        Assert.NotNull(roots);
+        Assert.Contains(roots!, view => view.Object.GobjectId == 1);
+        Assert.Contains(roots!, view => view.Object.GobjectId == 2);
+
+        // The orphan keeps its own deployed children nested beneath it.
+        Assert.True(index.ChildrenByParent.TryGetValue(2, out IReadOnlyList<GalaxyObjectView>? underOrphan));
+        Assert.Single(underOrphan!);
+        Assert.Equal(3, underOrphan![0].Object.GobjectId);
+
+        // Nothing buckets under the phantom parent id.
+        Assert.False(index.ChildrenByParent.ContainsKey(5008));
+    }
+
     /// <summary>Verifies <see cref="GalaxyHierarchyIndex.ObjectViewsByTagName"/> is OrdinalIgnoreCase and supports O(1) lookups.</summary>
     [Fact]
     public void ObjectViewsByTagName_IsCaseInsensitive_AndLookupsAreO1()