Add ultracode toggle that runs a request as a native dynamic workflow

A new transient per-request toggle state (off→plan→ultracode→fusion→moa)
that whitelists the CLI's Workflow + Task tools so Anthropic's native
dynamic-workflow orchestration runs in gott's headless -p mode without a
permission gate (the engine silently denies Workflow otherwise). Effort is
raised to xhigh (the real ultracode equivalent; "ultracode" itself is not a
valid effort value) without downgrading an explicit max. Only enabled for
Claude models (z.ai/GLM has no workflow runtime) and not in plan mode. The
frontend injects a "use a workflow" hint, like plan mode injects its own.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Models/ChatModels.cs

@@ -150,4 +150,12 @@ public class ChatRequest
     /// </summary>
     [JsonPropertyName("planMode")]
     public bool PlanMode { get; set; }
+
+    /// <summary>
+    /// Wenn true: Ultracode aktiv. Die Anfrage wird als nativer dynamischer Workflow
+    /// (mehrere Subagenten) gefahren – das Workflow-Tool wird freigeschaltet, Effort = xhigh.
+    /// Nur für den Claude-CLI-Pfad relevant (z.ai/GLM und der API-Pfad haben kein Workflow-Runtime).
+    /// </summary>
+    [JsonPropertyName("ultracode")]
+    public bool Ultracode { get; set; }
 }