feat(host-factory): register ChunkRenderer + PayloadHandler + Lender (F)

F adds the 3 new DI registrations needed for the v1.7.1 R-Block:

- ChunkRenderer (4-param ctor: themes, fonts, logger, gameFunctions)
- PayloadHandler singleton (7-param ctor: themes, ipc, functions,
  inputBar, mainWindow, chunkRenderer, logger)
- Lender<PayloadHandler> factory (closure over sp, constructs a fresh
  PayloadHandler per Borrow() — used by InputPreview in Sub-Task I)

All three use Factory-Lambdas because Lender<T> has an internal ctor and
ChunkRenderer/PayloadHandler are internal sealed (ActivatorUtilities
can't reflect into internal ctors per [[reference_hellion_chat_di_container_v150]]).

MainWindow DI-reg update is deferred to Sub-Task A2 (split per Flo
2026-05-27 to avoid the DI-cycle that would otherwise emerge from the
PayloadHandler → MainWindow → MessageList → PayloadHandler graph —
cycle resolved via setter-injection on MessageList in G/H).

G is next: wires PayloadHandlerInitHostedService.StartAsync to register
the AddonLifecycle listener for MoveTooltip and call MessageList.
AttachPayloadHandler. H adds the MessageList ChunkRenderer ctor-param +
AttachPayloadHandler setter.

HellionChat/PluginHostFactory.cs

@@ -225,6 +225,36 @@ internal static class PluginHostFactory
             );
         });
 
+        // Factory-lambdas for ChunkRenderer, PayloadHandler, and Lender<PayloadHandler>
+        // because all three are internal-sealed (ActivatorUtilities can't reflect into
+        // internal ctors) and Lender<T> has an internal ctor by design.
+        services.AddSingleton(sp => new Ui.Components.ChunkRenderer(
+            sp.GetRequiredService<ThemeRegistry>(),
+            sp.GetRequiredService<FontManager>(),
+            sp.GetRequiredService<ILogger<Ui.Components.ChunkRenderer>>(),
+            sp.GetRequiredService<GameFunctions.GameFunctions>()
+        ));
+        services.AddSingleton(sp => new PayloadHandler(
+            sp.GetRequiredService<ThemeRegistry>(),
+            sp.GetRequiredService<IpcManager>(),
+            sp.GetRequiredService<GameFunctions.GameFunctions>(),
+            sp.GetRequiredService<Ui.Components.InputBar>(),
+            sp.GetRequiredService<Ui.Windows.MainWindow>(),
+            sp.GetRequiredService<Ui.Components.ChunkRenderer>(),
+            sp.GetRequiredService<ILogger<PayloadHandler>>()
+        ));
+        services.AddSingleton(sp => new Lender<PayloadHandler>(() =>
+            new PayloadHandler(
+                sp.GetRequiredService<ThemeRegistry>(),
+                sp.GetRequiredService<IpcManager>(),
+                sp.GetRequiredService<GameFunctions.GameFunctions>(),
+                sp.GetRequiredService<Ui.Components.InputBar>(),
+                sp.GetRequiredService<Ui.Windows.MainWindow>(),
+                sp.GetRequiredService<Ui.Components.ChunkRenderer>(),
+                sp.GetRequiredService<ILogger<PayloadHandler>>()
+            )
+        ));
+
         // Block C — Windows. WindowSystem.AddWindow is called from
         // PluginLifecycle.LoadAsync on the framework thread.
         services.AddSingleton(sp => new Ui.Windows.SettingsWindow(