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>

wwwroot/css/chat.css

@@ -452,6 +452,11 @@
   background: color-mix(in srgb, var(--primary) 28%, transparent);
   border-radius: var(--border-radius);
 }
+#planModeBtn.ultracode-active {
+  color: var(--info);
+  background: color-mix(in srgb, var(--info) 18%, transparent);
+  border-radius: var(--border-radius);
+}
 
 /* Emoji Picker */