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/clients/client-tabs.tsx

@@ -11,6 +11,7 @@ import { RemindersInline } from '@/components/reminders/reminders-inline';
 import { primaryTimezoneFor } from '@/lib/i18n/timezones';
 import { InlineTagEditor } from '@/components/shared/inline-tag-editor';
 import { NotesList } from '@/components/shared/notes-list';
+import { ProxyCard } from '@/components/shared/proxy-card';
 import type { CountryCode } from '@/lib/i18n/countries';
 import { ClientInterestsTab } from '@/components/clients/client-interests-tab';
 import { ClientPipelineSummary } from '@/components/clients/client-pipeline-summary';
@@ -156,6 +157,9 @@ function OverviewTab({
           <ClientPipelineSummary clientId={clientId} variant="panel" />
         </div>
 
+        {/* CM-9: point-of-contact (default level for the client). */}
+        <ProxyCard entityType="client" entityId={clientId} />
+
         <div className="grid grid-cols-1 md:grid-cols-2 gap-6">
           {/* Personal Info */}
           <div className="space-y-1">