feat(api): GET/POST /api/v1/yachts

Add yacht list + create routes, export RouteHandler type and inner
handlers so tests can invoke them directly with a mock AuthContext.
New tests/helpers/route-tester.ts provides makeMockCtx/makeMockRequest
reusable by subsequent Task 3.x routes.

src/app/api/v1/yachts/route.ts

@@ -0,0 +1,47 @@
+import { NextResponse } from 'next/server';
+
+import { withAuth, withPermission, type RouteHandler } from '@/lib/api/helpers';
+import { parseQuery, parseBody } from '@/lib/api/route-helpers';
+import { errorResponse } from '@/lib/errors';
+import { listYachts, createYacht } from '@/lib/services/yachts.service';
+import { listYachtsSchema, createYachtSchema } from '@/lib/validators/yachts';
+
+export const listHandler: RouteHandler = async (req, ctx) => {
+  try {
+    const query = parseQuery(req, listYachtsSchema);
+    const result = await listYachts(ctx.portId, query);
+    const { page, limit } = query;
+    const totalPages = Math.ceil(result.total / limit);
+    return NextResponse.json({
+      data: result.data,
+      pagination: {
+        page,
+        pageSize: limit,
+        total: result.total,
+        totalPages,
+        hasNextPage: page < totalPages,
+        hasPreviousPage: page > 1,
+      },
+    });
+  } catch (error) {
+    return errorResponse(error);
+  }
+};
+
+export const createHandler: RouteHandler = async (req, ctx) => {
+  try {
+    const body = await parseBody(req, createYachtSchema);
+    const yacht = await createYacht(ctx.portId, body, {
+      userId: ctx.userId,
+      portId: ctx.portId,
+      ipAddress: ctx.ipAddress,
+      userAgent: ctx.userAgent,
+    });
+    return NextResponse.json({ data: yacht }, { status: 201 });
+  } catch (error) {
+    return errorResponse(error);
+  }
+};
+
+export const GET = withAuth(withPermission('yachts', 'view', listHandler));
+export const POST = withAuth(withPermission('yachts', 'create', createHandler));