ui: show no-agents banner on dashboard with link to onboarding step 2

When a company has no agents (e.g. user exited onboarding early), the
dashboard now shows an amber banner: "You have no agents. Create one
here" that opens the onboarding wizard directly at step 2 (agent
creation), skipping the company creation step.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

ui/src/pages/Companies.tsx

@@ -90,7 +90,7 @@ export function Companies() {
   return (
     <div className="space-y-6">
       <div className="flex items-center justify-end">
-        <Button size="sm" onClick={openOnboarding}>
+        <Button size="sm" onClick={() => openOnboarding()}>
           <Plus className="h-3.5 w-3.5 mr-1.5" />
           New Company
         </Button>

ui/src/pages/Dashboard.tsx

@@ -182,10 +182,29 @@ export function Dashboard() {
     return <PageSkeleton variant="dashboard" />;
   }
 
+  const hasNoAgents = agents !== undefined && agents.length === 0;
+
   return (
     <div className="space-y-6">
       {error && <p className="text-sm text-destructive">{error.message}</p>}
 
+      {hasNoAgents && (
+        <div className="flex items-center justify-between gap-3 rounded-md border border-amber-300 bg-amber-50 px-4 py-3 dark:border-amber-500/25 dark:bg-amber-950/60">
+          <div className="flex items-center gap-2.5">
+            <Bot className="h-4 w-4 text-amber-600 dark:text-amber-400 shrink-0" />
+            <p className="text-sm text-amber-900 dark:text-amber-100">
+              You have no agents.
+            </p>
+          </div>
+          <button
+            onClick={() => openOnboarding({ initialStep: 2, companyId: selectedCompanyId! })}
+            className="text-sm font-medium text-amber-700 hover:text-amber-900 dark:text-amber-300 dark:hover:text-amber-100 underline underline-offset-2 shrink-0"
+          >
+            Create one here
+          </button>
+        </div>
+      )}
+
       <ActiveAgentsPanel companyId={selectedCompanyId!} />
 
       {data && (