fix(build): extract route.ts handlers to handlers.ts (CLAUDE.md convention)

8 API route files were exporting handler functions directly from route.ts,
which Next.js 15 rejects with "$NAME is not a valid Route export field".
Per CLAUDE.md convention, service-tested handler functions live in sibling
handlers.ts files and route.ts only re-exports the GET/POST/etc. wrapped
in withAuth(withPermission(...)).

Discovered during the mobile-foundation Task 24 build validation; the route
files predate this branch but the build was never re-run on data-model.

Files:
- berth-reservations/[id], companies/autocomplete, companies/[id]/members
  + nested mid/set-primary, yachts/autocomplete, yachts/[id]/transfer,
  yachts/[id]/ownership-history
- Integration tests updated to import from handlers.ts (companies,
  memberships, reservations, yachts-detail)

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

src/app/api/v1/companies/[id]/members/handlers.ts

@@ -0,0 +1,40 @@
+import { NextResponse } from 'next/server';
+import { z } from 'zod';
+
+import { type RouteHandler } from '@/lib/api/helpers';
+import { parseBody, parseQuery } from '@/lib/api/route-helpers';
+import { errorResponse } from '@/lib/errors';
+import { addMembership, listByCompany } from '@/lib/services/company-memberships.service';
+import { addMembershipSchema } from '@/lib/validators/company-memberships';
+
+const listQuerySchema = z.object({
+  activeOnly: z
+    .enum(['true', 'false'])
+    .transform((v) => v === 'true')
+    .default('true'),
+});
+
+export const listHandler: RouteHandler = async (req, ctx, params) => {
+  try {
+    const { activeOnly } = parseQuery(req, listQuerySchema);
+    const memberships = await listByCompany(params.id!, ctx.portId, { activeOnly });
+    return NextResponse.json({ data: memberships });
+  } catch (error) {
+    return errorResponse(error);
+  }
+};
+
+export const createHandler: RouteHandler = async (req, ctx, params) => {
+  try {
+    const body = await parseBody(req, addMembershipSchema);
+    const membership = await addMembership(params.id!, ctx.portId, body, {
+      userId: ctx.userId,
+      portId: ctx.portId,
+      ipAddress: ctx.ipAddress,
+      userAgent: ctx.userAgent,
+    });
+    return NextResponse.json({ data: membership }, { status: 201 });
+  } catch (error) {
+    return errorResponse(error);
+  }
+};