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.Server/Galaxy/GalaxyHierarchyIndex.cs

@@ -106,6 +106,13 @@ public sealed class GalaxyHierarchyIndex
             {
                 parentKey = 0;
             }
+            // Re-root orphans whose parent object is absent from the set (e.g. a deleted or
+            // never-loaded container area). Otherwise they bucket under a phantom parent id
+            // that is never reached from the root, so they vanish from browse entirely.
+            else if (parentKey != 0 && !objectsById.ContainsKey(parentKey))
+            {
+                parentKey = 0;
+            }
             if (!childrenByParent.TryGetValue(parentKey, out List<GalaxyObjectView>? bucket))
             {
                 bucket = [];

src/ZB.MOM.WW.MxGateway.Server/Galaxy/GalaxyRepository.cs

@@ -172,6 +172,11 @@ public sealed class GalaxyRepository(GalaxyRepositoryOptions options) : IGalaxyR
             AckCommentSubtag = string.Empty,
         };
 
+    // Area objects (category 13) are returned even when undeployed (deployed_package_id = 0):
+    // they are organizational/model nodes that group deployed objects, so excluding them
+    // orphans every area whose containing area is not itself deployed. All non-area objects
+    // still require deployment. Orphans left by a missing/deleted parent area are re-rooted
+    // by GalaxyHierarchyIndex.Build so nothing disappears from browse.
     private const string HierarchySql = @"
 ;WITH template_chain AS (
     SELECT g.gobject_id AS instance_gobject_id, t.gobject_id AS template_gobject_id,
@@ -218,7 +223,7 @@ INNER JOIN template_definition td
     ON g.template_definition_id = td.template_definition_id
 WHERE td.category_id IN (1, 3, 4, 10, 11, 13, 17, 24, 26)
     AND g.is_template = 0
-    AND g.deployed_package_id <> 0
+    AND (g.deployed_package_id <> 0 OR td.category_id = 13)
 ORDER BY parent_gobject_id, g.tag_name";
 
     // Unlike HierarchySql, this query has diverged from the OtOpcUa original. It returns two

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()