fix(F17 ext): apply DetailNotFound to clients/yachts/companies/berths

Refactored the interest-detail 404 pattern into a reusable
`<DetailNotFound>` component and applied it to the four other entity
detail pages. Pre-fix, navigating to a wrong-port or stale entity URL
silently rendered the layout shell with empty tabs on:

  - /[portSlug]/clients/[id]
  - /[portSlug]/yachts/[id]
  - /[portSlug]/companies/[id]
  - /[portSlug]/berths/[id]

All four now route a 404/403 response into an explicit "<Entity> not
found" / "No access" EmptyState with a back-to-list CTA, and the
TanStack Query retry policy short-circuits 404/403s so the empty state
appears immediately.

1373/1373 vitest pass.

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

src/components/clients/client-detail.tsx

@@ -2,8 +2,10 @@
 
 import { useEffect } from 'react';
 import { useQuery } from '@tanstack/react-query';
+import { useParams } from 'next/navigation';
 
 import { DetailLayout } from '@/components/shared/detail-layout';
+import { DetailNotFound } from '@/components/shared/detail-not-found';
 import { useMobileChrome } from '@/components/layout/mobile/mobile-layout-provider';
 import { ClientDetailHeader } from '@/components/clients/client-detail-header';
 import { getClientTabs } from '@/components/clients/client-tabs';
@@ -79,10 +81,18 @@ interface ClientDetailProps {
 }
 
 export function ClientDetail({ clientId, currentUserId }: ClientDetailProps) {
-  const { data, isLoading } = useQuery<ClientData>({
+  const params = useParams<{ portSlug: string }>();
+  const portSlug = params?.portSlug ?? '';
+
+  const { data, isLoading, error } = useQuery<ClientData>({
     queryKey: ['clients', clientId],
     queryFn: () =>
       apiFetch<{ data: ClientData }>(`/api/v1/clients/${clientId}`).then((r) => r.data),
+    retry: (failureCount, err) => {
+      const status = (err as { status?: number } | null | undefined)?.status;
+      if (status === 404 || status === 403) return false;
+      return failureCount < 2;
+    },
   });
 
   const { setChrome } = useMobileChrome();
@@ -108,6 +118,18 @@ export function ClientDetail({ clientId, currentUserId }: ClientDetailProps) {
     'berth_reservation:cancelled': [['clients', clientId]],
   });
 
+  if (error && !isLoading) {
+    const status = (error as { status?: number } | null | undefined)?.status;
+    return (
+      <DetailNotFound
+        entity="client"
+        backHref={`/${portSlug}/clients`}
+        backLabel="Back to clients"
+        status={status}
+      />
+    );
+  }
+
   const tabs = data ? getClientTabs({ clientId, currentUserId, client: data }) : [];
 
   return (