feat(input-bar): wire slash-command callback + AllCommands (J2)

J2 closes the trigger-gap discovered in J review (2026-05-27): J
migrated CommandHelpWindow as a window but the v1.5.6 trigger-path
was never ported. J2 restores it:

- InputBar.cs adds ImGuiInputTextFlags.CallbackEdit + character-level
  callback that reads data.BufTextSpan, detects /-prefix, extracts
  command word, and calls _commandHelpWindow.Value.UpdateContent(desc)
- AllCommands.cs (new file, 1:1 port from v1.5.6) populates a static
  Dictionary<string, TextCommand> from Sheets.TextCommandSheet at
  startup; Plugin.CommandManager.Commands is the fallback for
  non-hardcoded commands
- CommandHelpWindow injected into InputBar via Lazy<T> ctor param to
  break the InputBar <-> CommandHelpWindow circular dep; PluginHostFactory
  DI-reg extended with the Lazy wrapper accordingly

Closes the smoke-step-9 gap. Phase-3 windows are now all reachable
end-to-end (R1 InputPreview, R2 CommandHelpWindow, R3 DebuggerWindow).

HellionChat/Ui/Components/InputBar.cs

@@ -1,10 +1,12 @@
 using System.Numerics;
+using System.Text;
 using Dalamud.Bindings.ImGui;
 using Dalamud.Interface;
 using Dalamud.Interface.Utility.Raii;
 using HellionChat.Code;
 using HellionChat.GameFunctions;
 using HellionChat.Themes;
+using HellionChat.Ui;
 using HellionChat.Ui.StyleEngine;
 using HellionChat.Util;
 using Microsoft.Extensions.Logging;
@@ -31,6 +33,7 @@ internal sealed class InputBar
     private readonly TokenResolver _resolver;
     private readonly ILogger<InputBar> _logger;
     private readonly Action _onOpenSettings;
+    private readonly Lazy<CommandHelpWindow> _commandHelpWindow;
 
     private string _pendingMessage = string.Empty;
     private bool _isFocused;
@@ -45,7 +48,8 @@ internal sealed class InputBar
         ThemeRegistry themes,
         TokenResolver resolver,
         ILogger<InputBar> logger,
-        Action onOpenSettings
+        Action onOpenSettings,
+        Lazy<CommandHelpWindow> commandHelpWindow
     )
     {
         _symbolPicker = symbolPicker;
@@ -54,6 +58,7 @@ internal sealed class InputBar
         _resolver = resolver;
         _logger = logger;
         _onOpenSettings = onOpenSettings;
+        _commandHelpWindow = commandHelpWindow;
     }
 
     public string PendingMessage => _pendingMessage;
@@ -221,15 +226,42 @@ internal sealed class InputBar
                 "##hellion-input",
                 ref _pendingMessage,
                 BufferCapacity,
-                ImGuiInputTextFlags.EnterReturnsTrue
+                ImGuiInputTextFlags.EnterReturnsTrue | ImGuiInputTextFlags.CallbackEdit,
+                SlashCommandCallback
             )
         )
         {
+            _commandHelpWindow.Value.IsOpen = false;
             TrySend(activeTab);
         }
         _isFocused = ImGui.IsItemFocused();
     }
 
+    // v1.5.6 character-level slash-detect: fires on every edit so CommandHelpWindow
+    // stays in sync with what the user is typing without a per-frame poll.
+    private int SlashCommandCallback(scoped ref ImGuiInputTextCallbackData data)
+    {
+        _commandHelpWindow.Value.IsOpen = false;
+        if (data.BufTextLen == 0)
+            return 0;
+
+        var text = Encoding.UTF8.GetString(data.BufTextSpan);
+        if (!text.StartsWith('/'))
+            return 0;
+
+        var spaceIdx = text.IndexOf(' ');
+        var command = spaceIdx > 0 ? text[..spaceIdx] : text;
+
+        if (AllCommands.TryGetValue(command, out var textCommand))
+            _commandHelpWindow.Value.UpdateContent(textCommand.Description);
+        else if (
+            Plugin.CommandManager.Commands.TryGetValue(command, out var info) && info.ShowInHelp
+        )
+            _commandHelpWindow.Value.UpdateContent(info.HelpMessage);
+
+        return 0;
+    }
+
     private void TrySend(Tab? activeTab)
     {
         var text = _pendingMessage.Trim();