fix(ui): profile page bugs - billing button, cancel button, header subtitle

- Remove billing portal button (not functional without Stripe configured)
- Show cancel subscription only when user has a real Stripe subscription ID
- Remove muted subtitle from dashboard header (was appearing as grayed out)

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

frontend/src/app/dashboard/DashboardHeader.tsx

@@ -55,8 +55,6 @@ export function DashboardHeader() {
         {/* Page title - desktop */}
         <div className="hidden items-center gap-3 lg:flex">
           <h1 className="text-sm font-semibold text-foreground">{t('dashboard.header.title')}</h1>
-          <Separator orientation="vertical" className="h-4" />
-          <span className="text-sm text-muted-foreground">{t('dashboard.header.subtitle')}</span>
         </div>
 
         {/* Right side */}

frontend/src/app/dashboard/profile/page.tsx

@@ -306,12 +306,6 @@ export default function ProfilePage() {
 
                 <div className="flex flex-wrap gap-2">
                   <Button asChild size="sm"><Link href="/pricing"><TrendingUp className="w-3.5 h-3.5 me-1.5" />{isFreePlan ? t('profile.subscription.upgradePlan') : t('profile.subscription.changePlan')}</Link></Button>
-                  {!isFreePlan && (
-                    <Button variant="outline" size="sm" onClick={handleBillingPortal} disabled={loadingPortal}>
-                      {loadingPortal ? <RefreshCw className="w-3.5 h-3.5 me-1.5 animate-spin" /> : <ExternalLink className="w-3.5 h-3.5 me-1.5" />}
-                      {t('profile.subscription.manageBilling')}
-                    </Button>
-                  )}
                 </div>
               </CardContent>
             </Card>
@@ -378,8 +372,8 @@ export default function ProfilePage() {
               </Card>
             )}
 
-            {/* Danger zone */}
-            {!isFreePlan && !isCanceling && (
+            {/* Danger zone - only show if user has a real Stripe subscription */}
+            {!isFreePlan && !isCanceling && user?.stripe_subscription_id && (
               <Card className="border-red-900/30">
                 <CardHeader className="pb-3">
                   <CardTitle className="text-base flex items-center gap-2 text-red-600 dark:text-red-400">