feat(input-bar): add SetPendingMessage/AppendPending mutators + Activate/FocusedPreview flags

Replaces v1.5.6's direct LogWindow.Chat mutation pattern with typed mutators
that LogWarning + clip/drop on BufferCapacity overflow (silent-overwrite
semantics preserved, but overflow is now observable via /xllog).

Plumbing for v1.7.1 PayloadHandler resurrection — DrawPlayerPopup (tell-
prefix) and DrawStatusPopup (status-link append) will call these mutators
instead of mutating a public field.

HellionChat/Ui/Components/InputBar.cs

@@ -36,6 +36,9 @@ internal sealed class InputBar
     private bool _isFocused;
     private bool? _isFocusedOverride; // Test-only; null = honour per-frame Draw() value.
 
+    public bool Activate;
+    public bool FocusedPreview;
+
     public InputBar(
         SymbolPicker symbolPicker,
         FontManager fonts,
@@ -69,6 +72,44 @@ internal sealed class InputBar
 
     public void ClearBuffer() => _pendingMessage = string.Empty;
 
+    // BufferCapacity is an ImGui UX limit, not a protocol constraint. We
+    // LogWarning + truncate/drop (matching v1.5.6's silent-overwrite semantics)
+    // so overflow is observable via /xllog without forcing try/catch at call-sites.
+    public void SetPendingMessage(string value)
+    {
+        if (value is null)
+            throw new ArgumentNullException(nameof(value));
+        if (value.Length > BufferCapacity)
+        {
+            _logger.LogWarning(
+                "SetPendingMessage: value of length {Length} exceeds BufferCapacity ({Capacity}); truncating.",
+                value.Length,
+                BufferCapacity
+            );
+            _pendingMessage = value[..BufferCapacity];
+        }
+        else
+        {
+            _pendingMessage = value;
+        }
+    }
+
+    public void AppendPending(string suffix)
+    {
+        if (string.IsNullOrEmpty(suffix))
+            return;
+        if (_pendingMessage.Length + suffix.Length > BufferCapacity)
+        {
+            _logger.LogWarning(
+                "AppendPending: appending {SuffixLength} chars would exceed BufferCapacity ({Capacity}); dropping suffix.",
+                suffix.Length,
+                BufferCapacity
+            );
+            return;
+        }
+        _pendingMessage += suffix;
+    }
+
     public void Draw(Tab? activeTab)
     {
         if (!_fonts.FontsReady)
@@ -168,6 +209,12 @@ internal sealed class InputBar
 
     private void DrawInputField(Tab? activeTab)
     {
+        if (Activate)
+        {
+            ImGui.SetKeyboardFocusHere();
+            Activate = false;
+        }
+
         ImGui.SetNextItemWidth(-QuickButtonsReserve);
         if (
             ImGui.InputText(