feat(uat-batch-14): InterestDocumentsTab rename, custom-field tooltip, yacht Transfer surface

- InterestDocumentsTab section "Legal documents" renamed to
  "Signature documents" so its scope is unambiguous. The section
  holds Documenso envelopes (EOI / Reservation / Contract); generic
  legal uploads belong in Attachments below.
- Custom-field admin form's "Sort Order" label now uses the
  FieldLabel primitive with an explainer tooltip ("Lower numbers
  render first... use to pin frequently-edited fields to the top").
  First adoption of the FieldLabel primitive shipped in PR4.2.
- Yacht Ownership History tab gains a "Transfer ownership" button:
  in the populated state as a header CTA (perm-gated by yachts.edit),
  in the empty state as the EmptyState action. Reuses the existing
  YachtTransferDialog from the header. Closes the "no way to enter/
  change" UX gap without duplicating the transfer logic.
- Verified the existing row-owner rendering already uses OwnerLink,
  so the row-click affordance was already in place.

tsc clean. 1419/1419 vitest pass.

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

src/components/admin/custom-fields/custom-field-form.tsx

@@ -7,6 +7,7 @@ import { Plus, X } from 'lucide-react';
 import { Button } from '@/components/ui/button';
 import { Input } from '@/components/ui/input';
 import { Label } from '@/components/ui/label';
+import { FieldLabel } from '@/components/ui/field-label';
 import { Switch } from '@/components/ui/switch';
 import {
   Dialog,
@@ -297,7 +298,12 @@ function CustomFieldFormBody({ open, onOpenChange, field, onSuccess }: CustomFie
 
           {/* Sort Order */}
           <div className="space-y-1.5">
-            <Label htmlFor="cf-sort-order">Sort Order</Label>
+            <FieldLabel
+              htmlFor="cf-sort-order"
+              tooltip="Lower numbers render first when the field set is shown on entity detail pages. Use to pin frequently-edited fields to the top."
+            >
+              Sort Order
+            </FieldLabel>
             <Input
               id="cf-sort-order"
               type="number"