feat(proxies): CM-9 UI — ProxyCard on client, interest, and yacht detail pages

- shared ProxyCard (view/add/edit/remove point-of-contact) reading each entity's
  /[id]/proxy sub-resource; permission-gated on the entity's edit right
- wired into the client overview, interest overview, and yacht overview tabs

Completes CM-9. tsc clean, lint 0 errors, prod build green, 1638 vitest pass.
Comms send-side wiring (route EOIs/emails through resolveEffectiveProxy) is a
deliberate follow-up — the resolver + data are ready for it.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/components/yachts/yacht-tabs.tsx

@@ -12,6 +12,7 @@ import { TenancyCreateDialog } from '@/components/tenancies/tenancy-create-dialo
 import { InlineEditableField } from '@/components/shared/inline-editable-field';
 import { FieldHistoryProvider, FieldHistoryIcon } from '@/components/shared/field-history';
 import { InlineTagEditor } from '@/components/shared/inline-tag-editor';
+import { ProxyCard } from '@/components/shared/proxy-card';
 import { NotesList } from '@/components/shared/notes-list';
 import { EntityActivityFeed } from '@/components/shared/entity-activity-feed';
 import { TenancyList, type TenancyRow } from '@/components/tenancies/tenancy-list';
@@ -176,6 +177,10 @@ function OverviewTab({
   return (
     <FieldHistoryProvider scope={{ type: 'yacht', id: yachtId }}>
       <div className="grid grid-cols-1 md:grid-cols-2 gap-6">
+        {/* CM-9: per-vessel point-of-contact (overrides interest + client). */}
+        <div className="md:col-span-2">
+          <ProxyCard entityType="yacht" entityId={yachtId} />
+        </div>
         {/* Identity */}
         <div className="space-y-1">
           <h3 className="text-sm font-medium mb-2">Identity</h3>