Add user settings, audit log, berth CRUD, and missing endpoints

- PATCH /api/v1/me: self-service profile update (name, phone, timezone)
- User settings page with profile editor + notification preferences
- Audit log API with filtering (entity, action, user, date range)
- Audit log page with search, entity type, and action filters
- Berth create/delete: POST /api/v1/berths + DELETE /api/v1/berths/[id]
- Client duplicates endpoint: GET /api/v1/clients/duplicates?name=
- Replace settings and audit stub pages with real implementations

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/app/api/v1/clients/duplicates/route.ts

@@ -0,0 +1,23 @@
+import { NextResponse } from 'next/server';
+import { z } from 'zod';
+
+import { withAuth, withPermission } from '@/lib/api/helpers';
+import { parseQuery } from '@/lib/api/route-helpers';
+import { findDuplicates } from '@/lib/services/clients.service';
+import { errorResponse } from '@/lib/errors';
+
+const duplicateQuerySchema = z.object({
+  name: z.string().min(1),
+});
+
+export const GET = withAuth(
+  withPermission('clients', 'view', async (req, ctx) => {
+    try {
+      const { name } = parseQuery(req, duplicateQuerySchema);
+      const data = await findDuplicates(ctx.portId, name);
+      return NextResponse.json({ data });
+    } catch (error) {
+      return errorResponse(error);
+    }
+  }),
+);