fix(invite): look up the invitation and route correctly (register vs sign in)

The invite link is token-only, so the landing page couldn't tell the invited
email or whether an account existed — it dumped everyone on an empty register
screen. Now it calls a public lookup (/api/invite/lookup → be-crm) and:
- first-time invitee → register with the email prefilled + locked;
- email already registered → sign in with the email prefilled;
- signed-in + registered → accept immediately; signed-in + no profile → onboarding.
Login now redeems the pending invite after sign-in (password/OTP/OAuth), so an
existing user's invite is accepted on login (not only when already logged in).

src/app/api/invite/lookup/route.ts

@@ -0,0 +1,28 @@
+import { NextResponse } from "next/server";
+
+// Server-side proxy to be-crm's public invitation lookup, so the invite landing page
+// can learn the invited email + roles and whether an account exists — before the
+// invitee has a session. Server-to-server avoids CORS. No secrets involved (the token
+// is the only credential, and it was emailed to the invitee).
+
+export const runtime = "nodejs";
+
+const CRM_BASE_URL = (process.env.CRM_BASE_URL ?? "https://crm.lynkedup.cloud").replace(/\/$/, "");
+
+export async function GET(request: Request) {
+  const token = new URL(request.url).searchParams.get("token") ?? "";
+  if (token.length < 16 || token.length > 256) {
+    return NextResponse.json({ ok: false, status: "invalid" }, { status: 400 });
+  }
+  try {
+    const res = await fetch(`${CRM_BASE_URL}/public/invitations/lookup?token=${encodeURIComponent(token)}`, {
+      headers: { Accept: "application/json" },
+      cache: "no-store",
+    });
+    if (!res.ok) return NextResponse.json({ ok: false, status: "unavailable" }, { status: 502 });
+    const data = await res.json();
+    return NextResponse.json(data);
+  } catch {
+    return NextResponse.json({ ok: false, status: "unavailable" }, { status: 502 });
+  }
+}