fix(mobile): hide duplicate detail-header title on mobile

The mobile topbar already shows the entity name pushed via
useMobileChrome, so the gradient detail-header strip was rendering it
a second time. Hides the inline h1 below sm: while keeping the source
/ email / phone meta and action buttons visible — the strip's
practical content (actions + meta) stays where users need it, and the
title responsibility moves cleanly to the topbar.

Affects: clients, yachts, companies, berths detail headers.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/components/clients/client-detail-header.tsx

@@ -74,7 +74,9 @@ export function ClientDetailHeader({ client }: ClientDetailHeaderProps) {
         <div className="flex items-start gap-3 flex-wrap">
           <div className="flex-1 min-w-0">
             <div className="flex items-center gap-2 flex-wrap">
-              <h1 className="text-2xl font-bold text-foreground truncate">{client.fullName}</h1>
+              <h1 className="hidden sm:block text-2xl font-bold text-foreground truncate">
+                {client.fullName}
+              </h1>
               {isArchived && (
                 <Badge variant="secondary" className="text-xs">
                   Archived