feat(style-engine): add PushStack as ImRaii bridge

DI-singleton that pairs Token lookups with ImRaii's tracked push/pop
machinery. Begin() returns a disposable PushScope with fluent Color, Style
(float/Vector2) and Font methods; reverse-order dispose runs through the
collected IDisposables. Counter-symmetry and exception-safety come from
ImRaii, this layer just handles the token → ImGuiCol resolution and the
RGBA → ABGR conversion at the ImGui boundary.

HellionChat/PluginHostFactory.cs

@@ -93,6 +93,9 @@ internal static class PluginHostFactory
         ));
 
         services.AddSingleton(_ => new Ui.StyleEngine.TokenResolver());
+        services.AddSingleton(sp => new Ui.StyleEngine.PushStack(
+            sp.GetRequiredService<Ui.StyleEngine.TokenResolver>()
+        ));
 
         services.AddSingleton(sp => new GameFunctions.GameFunctions(
             sp.GetRequiredService<Plugin>(),

HellionChat/Ui/StyleEngine/PushStack.cs

@@ -0,0 +1,71 @@
+using System.Numerics;
+using Dalamud.Bindings.ImGui;
+using Dalamud.Interface.ManagedFontAtlas;
+using Dalamud.Interface.Utility.Raii;
+using HellionChat.Themes;
+using HellionChat.Util;
+
+namespace HellionChat.Ui.StyleEngine;
+
+// Token-aware bridge over Dalamud's ImRaii. Couples semantic Token lookups
+// to the already-tracked push/pop machinery so callers express style intent
+// instead of raw ImGuiCol slots. Counter-symmetry and exception-safety come
+// from ImRaii, not from this class.
+internal sealed class PushStack
+{
+    private readonly TokenResolver _resolver;
+
+    public PushStack(TokenResolver resolver)
+    {
+        _resolver = resolver;
+    }
+
+    public PushScope Begin() => new(_resolver);
+
+    // Disposable scope handed to the using-block. Each Push.* call is a thin
+    // delegate to ImRaii / IFontHandle.Push with the token resolve in front;
+    // disposes in reverse order via the captured IDisposables.
+    internal sealed class PushScope : IDisposable
+    {
+        private readonly List<IDisposable> _items = new(32);
+        private readonly TokenResolver _resolver;
+
+        internal PushScope(TokenResolver resolver)
+        {
+            _resolver = resolver;
+        }
+
+        public PushScope Color(Token token, Theme theme)
+        {
+            var slot = TokenMap.ToImGuiCol(token);
+            var rgba = _resolver.Resolve(token, theme.Colors);
+            _items.Add(ImRaii.PushColor(slot, ColourUtil.RgbaToAbgr(rgba)));
+            return this;
+        }
+
+        public PushScope Style(ImGuiStyleVar var, float value)
+        {
+            _items.Add(ImRaii.PushStyle(var, value));
+            return this;
+        }
+
+        public PushScope Style(ImGuiStyleVar var, Vector2 value)
+        {
+            _items.Add(ImRaii.PushStyle(var, value));
+            return this;
+        }
+
+        public PushScope Font(IFontHandle font)
+        {
+            _items.Add(font.Push());
+            return this;
+        }
+
+        public void Dispose()
+        {
+            for (var i = _items.Count - 1; i >= 0; i--)
+                _items[i].Dispose();
+            _items.Clear();
+        }
+    }
+}