feat(tenancies-p6): module-gate entity tabs (berth / client / yacht)

- PortProvider exposes tenanciesModuleByPort + a useTenanciesModuleEnabled()
  hook that returns the flag for the currently-active port. Synchronous
  read off context (server-resolved in the dashboard layout), so no
  fetch latency / hydration flicker when the rep flips ports.
- buildBerthTabs / getClientTabs / getYachtTabs gain a
  tenanciesModuleEnabled option. When false, the Tenancies tab is
  filtered out entirely. When true, it slots into the entity-specific
  position (after Interests on berth + yacht; after Companies on client).
- BerthDetail / ClientDetail / YachtDetail pass the hook value through.
  Hook call ordered above the early-return so React's rules-of-hooks
  stays satisfied. Existing read-only tab content (Active tenancy card
  + History + the berth-side BerthReserveDialog "Create tenancy" CTA
  from P2) stays untouched — it just becomes visible when the module
  is on.

Deferred (separate ship): generic TenancyCreateDialog that pre-fills
clientId / yachtId from the parent entity context, so client / yacht
tabs can mint a tenancy without bouncing through the berth detail page.
Today client/yacht Tenancies tabs are read-only (the create entry-point
is the berth tab); the generic dialog will land alongside the Edit /
Renew / Transfer / End dialogs (design § P6 sub-tasks).

Verified: tsc clean, 1493/1493 vitest.

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

src/components/berths/berth-detail.tsx

@@ -8,6 +8,7 @@ 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 { apiFetch } from '@/lib/api/client';
+import { useTenanciesModuleEnabled } from '@/providers/port-provider';
 import { useRealtimeInvalidation } from '@/hooks/use-realtime-invalidation';
 import { BerthDetailHeader, type BerthDetailData } from './berth-detail-header';
 import { BerthForm } from './berth-form';
@@ -20,6 +21,7 @@ interface BerthDetailProps {
 export function BerthDetail({ berthId }: BerthDetailProps) {
   const params = useParams<{ portSlug: string }>();
   const portSlug = params?.portSlug ?? '';
+  const tenanciesModuleEnabled = useTenanciesModuleEnabled();
 
   const { data, isLoading, error } = useQuery<BerthDetailData>({
     queryKey: ['berth', berthId],
@@ -84,7 +86,7 @@ export function BerthDetail({ berthId }: BerthDetailProps) {
       <DetailLayout
         isLoading={isLoading}
         header={berth ? <BerthDetailHeader berth={berth} /> : null}
-        tabs={berth ? buildBerthTabs(berth) : []}
+        tabs={berth ? buildBerthTabs(berth, { tenanciesModuleEnabled }) : []}
         defaultTab="overview"
       />
       {berth ? <BerthForm berth={berth} open={editOpen} onOpenChange={setEditOpen} /> : null}

src/components/berths/berth-tabs.tsx

@@ -419,8 +419,11 @@ function OverviewTab({ berth }: { berth: BerthData }) {
   );
 }
 
-export function buildBerthTabs(berth: BerthData): DetailTab[] {
-  return [
+export function buildBerthTabs(
+  berth: BerthData,
+  opts: { tenanciesModuleEnabled: boolean } = { tenanciesModuleEnabled: false },
+): DetailTab[] {
+  const tabs: DetailTab[] = [
     {
       id: 'overview',
       label: 'Overview',
@@ -431,11 +434,20 @@ export function buildBerthTabs(berth: BerthData): DetailTab[] {
       label: 'Interests',
       content: <BerthInterestsTab berthId={berth.id} />,
     },
-    {
+  ];
+  if (opts.tenanciesModuleEnabled) {
+    tabs.push({
       id: 'tenancies',
       label: 'Tenancies',
       content: <BerthTenanciesTab berthId={berth.id} />,
-    },
+    });
+  }
+  tabs.push(...buildBerthDetailRemainder(berth));
+  return tabs;
+}
+
+function buildBerthDetailRemainder(berth: BerthData): DetailTab[] {
+  return [
     {
       id: 'spec',
       label: 'Spec',