Allow /api/register through auth middleware

The Turnstile/honeypot wrapper /api/register was missing from
PUBLIC_ROUTES, so unauthenticated POSTs were redirected to /login (307).
The register form followed the redirect, got HTML, and failed to parse
it — surfacing as "connection error". This silently broke signups for
new users. Add /api/register alongside /api/auth.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/middleware.ts

@@ -1,7 +1,7 @@
 import { NextRequest, NextResponse } from "next/server";
 import { getSessionCookie } from "better-auth/cookies";
 
-const PUBLIC_ROUTES = ["/login", "/register", "/verify-email", "/forgot-password", "/reset-password", "/api/auth", "/maintenance"];
+const PUBLIC_ROUTES = ["/login", "/register", "/verify-email", "/forgot-password", "/reset-password", "/api/auth", "/api/register", "/maintenance"];
 
 export function middleware(request: NextRequest) {
   const { pathname } = request.nextUrl;