style(detail): apply gradient header strip to client/interest/yacht/company/berth/residential/invoice details

Adds shared <DetailHeaderStrip> wrapper (rounded-xl + gradient-brand-soft + shadow-xs)
and applies it to every legacy domain detail header. Residential client/interest and
invoice detail get an inline gradient strip with eyebrow ('Residential Client',
'Residential Interest', 'Invoice'). Residential bodies normalized to lg:grid-cols-[2fr_1fr]
per spec.

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

src/components/shared/detail-header-strip.tsx

@@ -0,0 +1,20 @@
+import { type ReactNode } from 'react';
+import { cn } from '@/lib/utils';
+
+interface DetailHeaderStripProps {
+  children: ReactNode;
+  className?: string;
+}
+
+export function DetailHeaderStrip({ children, className }: DetailHeaderStripProps) {
+  return (
+    <div
+      className={cn(
+        'rounded-xl border border-slate-200 bg-gradient-brand-soft px-5 py-4 shadow-xs',
+        className,
+      )}
+    >
+      {children}
+    </div>
+  );
+}