feat(window): restore hide-chat-window + Enter-to-restore (1.5.6)

The eye/hide button now hides the HellionChat window (runtime-only, via a new
DrawConditions gate) instead of toggling native-chat suppression, matching 1.5.6.
The chat-activation keybind (Enter / "/"), whose dispatch was a dead stub in the
KeybindManager since the v1.6.0 rewrite, is re-wired to MainWindow.ActivateChat:
it un-hides, opens if closed, brings the window to front and focuses the input --
so the chat reacts to Enter again from any state. /hellion is a reliable one-press
recovery (Toggle now clears the hide), and the window always shows on login
(start state no longer read from the persisted flag). Adds HideRestoreSelfTestStep.

HellionChat/Ui/Components/InputBar.cs

@@ -45,6 +45,9 @@ internal sealed class InputBar
     // pop-out would be confusing). The main window's InputBar gets the instance.
     private readonly ThemeQuickPicker? _themeQuickPicker;
 
+    // Null in pop-outs (those have their own close button). Hides the main window.
+    private readonly Action? _onHideWindow;
+
     private string _pendingMessage = string.Empty;
     private bool _isFocused;
     private bool _wasInputTextHovered;
@@ -81,7 +84,8 @@ internal sealed class InputBar
         ILogger<InputBar> logger,
         Action onOpenSettings,
         CommandHelpWindow commandHelpWindow,
-        ThemeQuickPicker? themeQuickPicker = null
+        ThemeQuickPicker? themeQuickPicker = null,
+        Action? onHideWindow = null
     )
     {
         _symbolPicker = symbolPicker;
@@ -92,6 +96,7 @@ internal sealed class InputBar
         _onOpenSettings = onOpenSettings;
         _commandHelpWindow = commandHelpWindow;
         _themeQuickPicker = themeQuickPicker;
+        _onHideWindow = onHideWindow;
     }
 
     public string PendingMessage => _pendingMessage;
@@ -540,20 +545,17 @@ internal sealed class InputBar
                     ImGui.SetTooltip("Settings");
             }
 
-            // Hide button gated on ShowHideButton (1.5.6 parity). It is the last
-            // button in the row, so skipping it (with its leading SameLine) leaves
-            // no dangling SameLine. Shared by main + pop-out InputBars.
-            if (Plugin.Config.ShowHideButton)
+            // Hides the window (1.5.6 UserHide). One-way — Enter brings it back.
+            // Main window only (pop-outs have their own close); last in the row.
+            if (Plugin.Config.ShowHideButton && _onHideWindow is not null)
             {
                 ImGui.SameLine();
-                var hidden = Plugin.Config.HideChat;
-                var visIcon = hidden ? FontAwesomeIcon.EyeSlash : FontAwesomeIcon.Eye;
-                if (ImGui.Button(visIcon.ToIconString()))
-                    Plugin.Config.HideChat = !hidden;
+                if (ImGui.Button(FontAwesomeIcon.EyeSlash.ToIconString()))
+                    _onHideWindow();
                 if (ImGui.IsItemHovered())
                 {
                     using (ImRaii.DefaultFont())
-                        ImGui.SetTooltip(hidden ? "Unhide chat" : "Hide chat");
+                        ImGui.SetTooltip("Hide chat (Enter to bring back)");
                 }
             }
         }