feat(activity): per-entity Activity timeline (clients/yachts/companies/berths)

Until now only the global /admin/audit page surfaced audit_logs. Each
entity detail page either lacked the Activity tab entirely or rendered
"Activity log coming soon" text.

- entity-activity.service.loadEntityActivity wraps searchAuditLogs
  with actor-email resolution; reused by all 5 endpoints.
- New endpoints: /api/v1/{clients,yachts,companies,berths,interests}/[id]/activity,
  each gated on the per-entity .view permission and tenant-checked
  against ctx.portId.
- EntityActivityFeed renders a timeline with action verb ("Updated",
  "Archived"), actor name, relative time, and field old→new diff.
- client-tabs, yacht-tabs, company-tabs, berth-tabs now mount the feed
  on their Activity tab. Interest already has the richer
  InterestTimeline component.
- yacht-tabs YachtInterestsTab also gets a friendlier empty state with
  guidance copy.

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

src/components/clients/client-tabs.tsx

@@ -16,6 +16,7 @@ import { ClientCompaniesTab } from '@/components/clients/client-companies-tab';
 import { ClientReservationsTab } from '@/components/clients/client-reservations-tab';
 import { ContactsEditor } from '@/components/clients/contacts-editor';
 import { AddressesEditor, type Address } from '@/components/shared/addresses-editor';
+import { EntityActivityFeed } from '@/components/shared/entity-activity-feed';
 import { apiFetch } from '@/lib/api/client';
 
 type ClientPatchField =
@@ -280,9 +281,10 @@ export function getClientTabs({ clientId, currentUserId, client }: ClientTabsOpt
       id: 'activity',
       label: 'Activity',
       content: (
-        <div className="text-center py-12 text-muted-foreground">
-          <p>Activity log coming soon.</p>
-        </div>
+        <EntityActivityFeed
+          endpoint={`/api/v1/clients/${clientId}/activity`}
+          emptyText="No activity recorded for this client yet."
+        />
       ),
     },
   ];