feat(tenancies-p6-followup): generic create dialog + edit dialog + self-FKs

- Migration 0086: berth_tenancies.previous_tenancy_id +
  transferred_from_tenancy_id self-FKs + partial indexes. Per
  docs/tenancies-design.md these chain renewal / transfer successors
  to predecessors for fixed-term and seasonal lineage. Schema mirrored
  in tenancies.ts with AnyPgColumn typed-import.
- POST /api/v1/tenancies (generic create): accepts berthId in the
  body so client + yacht tab entry points don't have to bounce through
  /api/v1/berths/[id]/tenancies. Same createPending service helper.
- TenancyCreateDialog: <TenancyCreateDialog open clientId? yachtId?
  berthId? /> with all three pickers; pre-fills the carrier from the
  parent entity. POSTs to /api/v1/tenancies; "Create" and
  "Create and activate" CTAs both wire to the new endpoint.
- Mounted on ClientTenanciesTab + YachtTenanciesTab behind
  <PermissionGate resource="tenancies" action="manage"> so reps can
  mint tenancies directly from those tabs without bouncing through
  the berth page.
- TenancyEditDialog: edit metadata only (start/end dates, tenure type,
  notes) via the new action='update' branch on the [id] PATCH route.
  Status transitions stay on activate/end/cancel. Wired into the
  tenancy detail page header. Outer wrapper unmounts on close so the
  form re-initialises from current row data without setState-in-effect.
- updateTenancy service helper + PATCH action='update' branch added.
  Audit-logged + emits berth_tenancy:activated to invalidate detail
  query caches.

Renew + Transfer dialogs deferred — both need lineage UX decisions
(tenure-aware mutate-in-place vs new-row spawn; client/yacht swap
semantics) and the self-FK columns this commit lands are the
underpinning. Next sub-task.

Verified: tsc clean, 1493/1493 vitest, migration applied.

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

src/components/yachts/yacht-tabs.tsx

@@ -1,9 +1,14 @@
 'use client';
 
+import { useState } from 'react';
 import { useMutation, useQuery, useQueryClient } from '@tanstack/react-query';
 import { useParams } from 'next/navigation';
+import { Plus } from 'lucide-react';
 
 import type { DetailTab } from '@/components/shared/detail-layout';
+import { Button } from '@/components/ui/button';
+import { PermissionGate } from '@/components/shared/permission-gate';
+import { TenancyCreateDialog } from '@/components/tenancies/tenancy-create-dialog';
 import { InlineEditableField } from '@/components/shared/inline-editable-field';
 import { FieldHistoryProvider, FieldHistoryIcon } from '@/components/shared/field-history';
 import { InlineTagEditor } from '@/components/shared/inline-tag-editor';
@@ -337,6 +342,7 @@ function YachtInterestsTab({ yachtId }: { yachtId: string }) {
 function YachtTenanciesTab({ yachtId }: { yachtId: string }) {
   const routeParams = useParams<{ portSlug: string }>();
   const portSlug = routeParams?.portSlug ?? '';
+  const [createOpen, setCreateOpen] = useState(false);
 
   const { data, isLoading } = useQuery<{ data: TenancyRow[] }>({
     queryKey: ['tenancies', 'by-yacht', yachtId],
@@ -346,12 +352,23 @@ function YachtTenanciesTab({ yachtId }: { yachtId: string }) {
   if (isLoading) return <p className="text-sm text-muted-foreground">Loading…</p>;
 
   return (
-    <TenancyList
-      tenancies={data?.data ?? []}
-      showBerth
-      portSlug={portSlug}
-      emptyMessage="No tenancies for this yacht."
-    />
+    <div className="space-y-4">
+      <div className="flex items-center justify-end">
+        <PermissionGate resource="tenancies" action="manage">
+          <Button size="sm" onClick={() => setCreateOpen(true)}>
+            <Plus className="mr-1.5 h-4 w-4" aria-hidden />
+            Create tenancy
+          </Button>
+        </PermissionGate>
+      </div>
+      <TenancyList
+        tenancies={data?.data ?? []}
+        showBerth
+        portSlug={portSlug}
+        emptyMessage="No tenancies for this yacht."
+      />
+      <TenancyCreateDialog open={createOpen} onOpenChange={setCreateOpen} yachtId={yachtId} />
+    </div>
   );
 }