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/clients/client-tenancies-tab.tsx

@@ -3,7 +3,11 @@
 import { useState } from 'react';
 import { useQuery } from '@tanstack/react-query';
 
+import { Plus } from 'lucide-react';
+
 import { TenancyList, type TenancyRow } from '@/components/tenancies/tenancy-list';
+import { TenancyCreateDialog } from '@/components/tenancies/tenancy-create-dialog';
+import { PermissionGate } from '@/components/shared/permission-gate';
 import { Button } from '@/components/ui/button';
 import { apiFetch } from '@/lib/api/client';
 
@@ -26,6 +30,7 @@ interface TenancyListResponse {
 
 export function ClientTenanciesTab({ clientId, activeTenancies }: ClientTenanciesTabProps) {
   const [showHistory, setShowHistory] = useState(false);
+  const [createOpen, setCreateOpen] = useState(false);
 
   const activeRows: TenancyRow[] = activeTenancies.map((r) => ({
     id: r.id,
@@ -73,6 +78,12 @@ export function ClientTenanciesTab({ clientId, activeTenancies }: ClientTenancie
       <div>
         <div className="flex items-center justify-between">
           <h3 className="text-sm font-medium">Active tenancies</h3>
+          <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={activeRows}
@@ -109,6 +120,8 @@ export function ClientTenanciesTab({ clientId, activeTenancies }: ClientTenancie
           </p>
         )}
       </div>
+
+      <TenancyCreateDialog open={createOpen} onOpenChange={setCreateOpen} clientId={clientId} />
     </div>
   );
 }