feat(chat): route retail lifestone commands

Separate retail client actions, ACE server commands, and ordinary chat at the shared router. Port lifestone/lif/ls from the named retail registry through a typed App controller to game action 0x0063, keep unknown verbs on ACE Talk, and cover both UI backends plus exact outbound bytes.

Co-Authored-By: Codex <codex@openai.com>

src/AcDream.UI.Abstractions/Panels/Chat/RetailClientCommandCatalog.cs

@@ -0,0 +1,90 @@
+using System.Collections.Frozen;
+
+namespace AcDream.UI.Abstractions.Panels.Chat;
+
+/// <summary>
+/// Immutable catalog of commands the named retail client executes locally.
+/// This is intentionally separate from chat aliases and ACE server commands.
+///
+/// <para>
+/// First vertical slice: retail registers <c>lifestone</c>, <c>lif</c>, and
+/// <c>ls</c> against <c>ClientCommunicationSystem::DoLifestone @ 0x0056FC70</c>.
+/// See <c>docs/research/2026-07-13-retail-client-command-routing-pseudocode.md</c>.
+/// </para>
+/// </summary>
+public static class RetailClientCommandCatalog
+{
+    private sealed record Definition(
+        ClientCommandId Command,
+        string Usage,
+        string HelpText,
+        Func<string, bool> ValidateArguments);
+
+    /// <summary>A resolved retail command plus its raw, trimmed argument text.</summary>
+    public readonly record struct Match(
+        ClientCommandId Command,
+        string Arguments,
+        string Usage,
+        bool HasValidArguments);
+
+    private static readonly Definition Lifestone = new(
+        ClientCommandId.LifestoneRecall,
+        Usage: "/lifestone",
+        HelpText: "/lifestone (/lif, /ls) - Returns you to the last lifestone you used without killing you.",
+        ValidateArguments: static arguments => arguments.Length == 0);
+
+    private static readonly FrozenDictionary<string, Definition> ByVerb =
+        new Dictionary<string, Definition>(StringComparer.OrdinalIgnoreCase)
+        {
+            ["lifestone"] = Lifestone,
+            ["lif"] = Lifestone,
+            ["ls"] = Lifestone,
+        }.ToFrozenDictionary(StringComparer.OrdinalIgnoreCase);
+
+    /// <summary>
+    /// Resolve a complete chat-bar line. Returns false when its verb is not
+    /// client-owned; callers can then try chat aliases or the server-command
+    /// path. Both retail command prefixes are accepted.
+    /// </summary>
+    public static bool TryMatch(string input, out Match match)
+    {
+        match = default;
+        if (string.IsNullOrWhiteSpace(input))
+            return false;
+
+        string trimmed = input.Trim();
+        if (trimmed.Length < 2 || trimmed[0] is not ('/' or '@'))
+            return false;
+
+        int separator = IndexOfWhitespace(trimmed);
+        string verb = separator < 0
+            ? trimmed[1..]
+            : trimmed.Substring(1, separator - 1);
+        if (!ByVerb.TryGetValue(verb, out Definition? definition))
+            return false;
+
+        string arguments = separator < 0
+            ? string.Empty
+            : trimmed[(separator + 1)..].Trim();
+        match = new Match(
+            definition.Command,
+            arguments,
+            definition.Usage,
+            definition.ValidateArguments(arguments));
+        return true;
+    }
+
+    /// <summary>Help line generated from the same definition routing uses.</summary>
+    public static string BuildHelpText() => Lifestone.HelpText;
+
+    private static int IndexOfWhitespace(string value)
+    {
+        for (int i = 1; i < value.Length; i++)
+        {
+            if (char.IsWhiteSpace(value[i]))
+                return i;
+        }
+
+        return -1;
+    }
+}