feat(settings): claude_bin im Dateien-Tab setzbar, mit Auflösungs-Check

Bisher nur per Hand in worker.config.json. Neuer Abschnitt CLAUDE CLI mit
eigenem Save-Button (die Datei gehoert dem Worker, nicht app_settings) und einer
Zeile, wohin der Wert per ExecutableResolver tatsaechlich aufloest — 'nicht im
PATH gefunden' war bisher erst am fehlgeschlagenen Run zu sehen. WorkerConfig ist
DI-Singleton und ClaudeProcess loest pro Spawn auf, also greift die Aenderung ab
dem naechsten Run ohne Neustart.

SaveOnlineInbox/SaveClaudeBin teilen jetzt ein SaveKey(), damit beide dieselbe
read-modify-write-Semantik haben (alle anderen Keys bleiben unberuehrt).
Die zugehoerigen Locale-Keys sind im vorigen Commit mitgelaufen.

src/ClaudeDo.Worker/Config/WorkerConfig.cs

@@ -96,6 +96,14 @@ public sealed class WorkerConfig
     /// Reads the existing JSON, replaces the <c>online_inbox</c> node, and writes back indented.
     /// </summary>
     public void SaveOnlineInbox(string? path = null)
+        => SaveKey("online_inbox", JsonSerializer.SerializeToNode(OnlineInbox, InboxSerializerOpts), path);
+
+    /// <summary>Persists ONLY <c>claude_bin</c>, same read-modify-write as
+    /// <see cref="SaveOnlineInbox"/> — every other field in the file stays untouched.</summary>
+    public void SaveClaudeBin(string? path = null)
+        => SaveKey("claude_bin", JsonValue.Create(ClaudeBin), path);
+
+    private static void SaveKey(string key, JsonNode? value, string? path)
     {
         path ??= DefaultConfigPath;
 
@@ -103,7 +111,7 @@ public sealed class WorkerConfig
             ? JsonNode.Parse(File.ReadAllText(path)) as JsonObject ?? new JsonObject()
             : new JsonObject();
 
-        root["online_inbox"] = JsonSerializer.SerializeToNode(OnlineInbox, InboxSerializerOpts);
+        root[key] = value;
 
         Directory.CreateDirectory(Path.GetDirectoryName(path)!);
         File.WriteAllText(path, root.ToJsonString(WriteOpts));

src/ClaudeDo.Worker/Hub/WorkerHub.cs

@@ -1,6 +1,7 @@
 using System.Globalization;
 using System.Reflection;
 using ClaudeDo.Data;
+using ClaudeDo.Data.Environment;
 using ClaudeDo.Data.Models;
 using ClaudeDo.Data.Repositories;
 using ClaudeDo.Worker.Agents;
@@ -1000,6 +1001,22 @@ public sealed class WorkerHub : Microsoft.AspNetCore.SignalR.Hub
         return ids.Count;
     }
 
+    public ClaudeBinDto GetClaudeBin() => DescribeClaudeBin();
+
+    /// Blank resets to the plain "claude" command. WorkerConfig is a DI singleton and
+    /// ClaudeProcess resolves it per spawn, so the change applies to the next run without a
+    /// restart — but it is persisted too, since Load() re-reads the file on startup.
+    public ClaudeBinDto SetClaudeBin(string? value)
+    {
+        _cfg.ClaudeBin = string.IsNullOrWhiteSpace(value) ? "claude" : value.Trim();
+        _cfg.SaveClaudeBin();
+        _ = _broadcaster.WorkerLog($"claude_bin set to '{_cfg.ClaudeBin}'", WorkerLogLevel.Info, DateTime.UtcNow);
+        return DescribeClaudeBin();
+    }
+
+    private ClaudeBinDto DescribeClaudeBin() =>
+        new(_cfg.ClaudeBin, ExecutableResolver.Resolve(_cfg.ClaudeBin)?.Path);
+
 #pragma warning disable CA1416 // ClaudeDo.Worker is Windows-only; DPAPI calls are safe here.
     public OnlineInboxStateDto GetOnlineInboxState()
     {