feat(ui): port retail toolbar ammo count

Resolve stacked thrown weapons versus separately equipped missile ammo exactly like gmToolbarUI, normalize a zero stack to one, and refresh the authored missile indicator from equipment and stack events. Keep the decision in pure Core with retained and real-DAT conformance coverage.

Co-Authored-By: Codex <codex@openai.com>

tests/AcDream.App.Tests/UI/Layout/ToolbarControllerTests.cs

@@ -336,6 +336,17 @@ public class ToolbarControllerTests
         }
     }
 
+    [Fact]
+    public void RetailFixture_ammoNumberUsesAuthoredMissileIndicatorElement()
+    {
+        ImportedLayout layout = FixtureLoader.LoadToolbar();
+
+        var ammoIndicator = Assert.IsType<UiButton>(layout.FindElement(0x10000194u));
+
+        Assert.Equal(55f, ammoIndicator.Width);
+        Assert.Equal(58f, ammoIndicator.Height);
+    }
+
     [Fact]
     public void UseAndExamineButtons_dispatchSelectedObjectPolicy()
     {
@@ -387,6 +398,76 @@ public class ToolbarControllerTests
 
     // ── C1: combat-mode indicator tests ─────────────────────────────────────
 
+    [Fact]
+    public void AmmoNumber_usesStackableMissileWeapon_andTracksStackChanges()
+    {
+        const uint player = 0x50000001u;
+        const uint thrownWeapon = 0x50000002u;
+        const uint separateAmmo = 0x50000003u;
+        var (layout, _, _) = FakeToolbar();
+        var repo = new ClientObjectTable();
+        repo.AddOrUpdate(new ClientObject { ObjectId = player, Type = ItemType.Creature });
+        repo.AddOrUpdate(new ClientObject
+        {
+            ObjectId = thrownWeapon,
+            StackSize = 7,
+            StackSizeMax = 25,
+        });
+        repo.MoveItem(thrownWeapon, player, newEquipLocation: EquipMask.MissileWeapon);
+        repo.AddOrUpdate(new ClientObject
+        {
+            ObjectId = separateAmmo,
+            StackSize = 80,
+            StackSizeMax = 100,
+        });
+        repo.MoveItem(separateAmmo, player, newEquipLocation: EquipMask.MissileAmmo);
+
+        ToolbarController.Bind(
+            layout,
+            repo,
+            () => Array.Empty<ShortcutEntry>(),
+            iconIds: (_, _, _, _, _) => 0u,
+            useItem: _ => { },
+            playerGuid: () => player);
+        var ammoButton = (UiButton)layout.FindElement(0x10000194u)!;
+
+        Assert.Equal("7", ammoButton.Label);
+
+        Assert.True(repo.UpdateStackSize(thrownWeapon, 6, value: 0));
+        Assert.Equal("6", ammoButton.Label);
+    }
+
+    [Fact]
+    public void AmmoNumber_forLauncher_usesAmmoSlot_andClearsOnUnwield()
+    {
+        const uint player = 0x50000001u;
+        const uint pack = 0x50000010u;
+        const uint bow = 0x50000002u;
+        const uint arrows = 0x50000003u;
+        var (layout, _, _) = FakeToolbar();
+        var repo = new ClientObjectTable();
+        repo.AddOrUpdate(new ClientObject { ObjectId = player, Type = ItemType.Creature });
+        repo.AddOrUpdate(new ClientObject { ObjectId = pack, Type = ItemType.Container });
+        repo.AddOrUpdate(new ClientObject { ObjectId = bow, StackSize = 1, StackSizeMax = 1 });
+        repo.MoveItem(bow, player, newEquipLocation: EquipMask.MissileWeapon);
+        repo.AddOrUpdate(new ClientObject { ObjectId = arrows, StackSize = 42, StackSizeMax = 100 });
+        repo.MoveItem(arrows, player, newEquipLocation: EquipMask.MissileAmmo);
+
+        ToolbarController.Bind(
+            layout,
+            repo,
+            () => Array.Empty<ShortcutEntry>(),
+            iconIds: (_, _, _, _, _) => 0u,
+            useItem: _ => { },
+            playerGuid: () => player);
+        var ammoButton = (UiButton)layout.FindElement(0x10000194u)!;
+
+        Assert.Equal("42", ammoButton.Label);
+
+        Assert.True(repo.MoveItem(arrows, pack));
+        Assert.Null(ammoButton.Label);
+    }
+
     [Fact]
     public void CombatIndicators_allDispatchSharedRetailToggleCommand()
     {