chore(style): add a widget gallery for visual verification

Every widget in its states, reachable via /hellion widgets. The point is to
check them one at a time before they land in real components: the v2.x style
engine grew three primitives that were never wired to a call site
(DrawGlowBorder, DrawSlipPolygon, DrawHonorificHeader), and this is the cheap
way to notice that before a cycle closes.

DEBUG-only, like SeStringDebugger. It is a verification aid, not a feature, so
it never reaches a release build -- verified against a Release compile.

The header line also shows the live GlobalScale and the hover registry size,
which makes both the scaling work and the eviction contract observable while
dragging the Dalamud scale slider.

HellionChat/Plugin.cs

@@ -109,6 +109,9 @@ public sealed class Plugin : IAsyncDalamudPlugin
     internal static InputPreview InputPreview { get; private set; } = null!;
     internal CommandHelpWindow CommandHelpWindow { get; private set; } = null!;
     public SeStringDebugger SeStringDebugger { get; private set; } = null!;
+#if DEBUG
+    internal Ui.Windows.WidgetGalleryWindow WidgetGallery { get; private set; } = null!;
+#endif
     public FirstRunWizard FirstRunWizard { get; private set; } = null!;
     internal DebuggerWindow DebuggerWindow { get; private set; } = null!;
 
@@ -365,6 +368,9 @@ public sealed class Plugin : IAsyncDalamudPlugin
         InputPreview = _host.Services.GetRequiredService<InputPreview>();
         CommandHelpWindow = _host.Services.GetRequiredService<CommandHelpWindow>();
         SeStringDebugger = _host.Services.GetRequiredService<SeStringDebugger>();
+#if DEBUG
+        WidgetGallery = _host.Services.GetRequiredService<Ui.Windows.WidgetGalleryWindow>();
+#endif
         DebuggerWindow = _host.Services.GetRequiredService<DebuggerWindow>();
         FirstRunWizard = _host.Services.GetRequiredService<FirstRunWizard>();
         ChannelPopoutPool = _host.Services.GetRequiredService<Ui.Windows.ChannelPopoutPool>();
@@ -925,6 +931,13 @@ public sealed class Plugin : IAsyncDalamudPlugin
             SettingsWindow.Toggle();
             return;
         }
+#if DEBUG
+        if (arg.Equals("widgets", StringComparison.OrdinalIgnoreCase))
+        {
+            WidgetGallery.Toggle();
+            return;
+        }
+#endif
         if (arg.Equals("reset", StringComparison.OrdinalIgnoreCase))
         {
             // Recovery path documented in the v2.x master spec — drops a