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/app/api/v1/companies/[id]/activity/route.ts

@@ -0,0 +1,31 @@
+import { NextResponse } from 'next/server';
+import { eq, and } from 'drizzle-orm';
+
+import { withAuth, withPermission } from '@/lib/api/helpers';
+import { db } from '@/lib/db';
+import { companies } from '@/lib/db/schema/companies';
+import { loadEntityActivity } from '@/lib/services/entity-activity.service';
+import { errorResponse, NotFoundError } from '@/lib/errors';
+
+export const GET = withAuth(
+  withPermission('companies', 'view', async (_req, ctx, params) => {
+    try {
+      const id = params.id;
+      if (!id) throw new NotFoundError('company');
+      const exists = await db
+        .select({ id: companies.id })
+        .from(companies)
+        .where(and(eq(companies.id, id), eq(companies.portId, ctx.portId)))
+        .limit(1);
+      if (exists.length === 0) throw new NotFoundError('company');
+      const data = await loadEntityActivity({
+        portId: ctx.portId,
+        entityType: 'company',
+        entityId: id,
+      });
+      return NextResponse.json({ data });
+    } catch (error) {
+      return errorResponse(error);
+    }
+  }),
+);