Move inviteRequestSchema out of route.ts to satisfy Next 15 build

Next.js 15 enforces a strict allowlist of named exports from route.ts
files; "inviteRequestSchema" was rejected by the route-validator with
"is not a valid Route export field" during npm run build. Splitting the
schema into a sibling module (which is exempt from the allowlist) and
importing it from route.ts and the test. Renames the test file to
match its target module.

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

src/app/api/portfolio/[portfolioId]/collaborators/inviteRequestSchema.test.ts

@@ -1,6 +1,6 @@
 import { describe, expect, it } from "vitest";
 
-import { inviteRequestSchema } from "./route";
+import { inviteRequestSchema } from "./inviteRequestSchema";
 
 describe("inviteRequestSchema", () => {
   it("accepts an invite request with just email and role (no name)", () => {

src/app/api/portfolio/[portfolioId]/collaborators/inviteRequestSchema.ts

@@ -0,0 +1,10 @@
+import { z } from "zod";
+import { ROLE_OPTIONS } from "@/app/portfolio/[slug]/(portfolio)/settings/roles";
+
+// Body schema for POST /api/portfolio/[portfolioId]/collaborators. Lives in
+// its own file because Next.js 15 rejects non-handler named exports from
+// route.ts. See route.test.ts for the contract tests.
+export const inviteRequestSchema = z.object({
+  email: z.string().email(),
+  role: z.enum(ROLE_OPTIONS),
+});

src/app/api/portfolio/[portfolioId]/collaborators/route.ts

@@ -29,6 +29,7 @@ import {
   denyIfNotAdmin,
   resolvePortfolioPrivilege,
 } from "@/app/lib/resolvePortfolioPrivilege";
+import { inviteRequestSchema } from "./inviteRequestSchema";
 
 // Get collaborators (users) that have access to the portfolio, plus the
 // effective privilege of the requesting user (so the UI knows which actions
@@ -192,13 +193,6 @@ export async function PUT(
   }
 }
 
-// Body schema for the invite endpoint. Exported so the contract can be
-// unit-tested directly — see route.test.ts.
-export const inviteRequestSchema = z.object({
-  email: z.string().email(),
-  role: z.enum(ROLE_OPTIONS),
-});
-
 // POST: invite a user by email.
 //
 // Unified flow: in nearly every case we write a pending portfolio_invitations