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/shared/detail-not-found.tsx

@@ -0,0 +1,48 @@
+'use client';
+
+import { SearchX } from 'lucide-react';
+
+import { EmptyState } from '@/components/shared/empty-state';
+
+interface DetailNotFoundProps {
+  /** "interest", "client", "yacht", etc. — used to build the copy. */
+  entity: string;
+  /** Plural list path back-link. e.g. "/port-x/clients". */
+  backHref: string;
+  /** Plural label for the back button, e.g. "Back to clients". */
+  backLabel: string;
+  /** HTTP status code from the failed fetch (404 vs 403 changes copy). */
+  status?: number;
+}
+
+/**
+ * Renders an explicit "not found" / "no access" panel for entity detail
+ * pages whose data fetch failed. Replaces the prior silent-list-shell
+ * behaviour where a wrong-port URL paste rendered the navigation chrome
+ * with empty tabs and no error message. Post-audit F17.
+ */
+export function DetailNotFound({ entity, backHref, backLabel, status }: DetailNotFoundProps) {
+  const denied = status === 403;
+  return (
+    <EmptyState
+      icon={SearchX}
+      title={denied ? `No access to this ${entity}` : `${capitalize(entity)} not found`}
+      description={
+        denied
+          ? `You do not have permission to view this ${entity} in this port.`
+          : `It may have been removed, archived, or it belongs to a different port. Use the back button or pick a different ${entity}.`
+      }
+      className="mt-16"
+      action={{
+        label: backLabel,
+        onClick: () => {
+          window.location.assign(backHref);
+        },
+      }}
+    />
+  );
+}
+
+function capitalize(s: string) {
+  return s.charAt(0).toUpperCase() + s.slice(1);
+}