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/berths/berth-tabs.tsx

@@ -3,6 +3,7 @@
 import { type DetailTab } from '@/components/shared/detail-layout';
 import { Card, CardContent, CardHeader, CardTitle } from '@/components/ui/card';
 import { TagBadge } from '@/components/shared/tag-badge';
+import { EntityActivityFeed } from '@/components/shared/entity-activity-feed';
 import { BerthReservationsTab } from './berth-reservations-tab';
 import { BerthInterestsTab } from './berth-interests-tab';
 import { BerthInterestPulse } from './berth-interest-pulse';
@@ -250,7 +251,12 @@ export function buildBerthTabs(berth: BerthData): DetailTab[] {
     {
       id: 'activity',
       label: 'Activity',
-      content: <StubTab label="Activity" />,
+      content: (
+        <EntityActivityFeed
+          endpoint={`/api/v1/berths/${berth.id}/activity`}
+          emptyText="No activity recorded for this berth yet."
+        />
+      ),
     },
   ];
 }