fix(referrals): test expectations don't match route implementation

[forgou37]

Bug

Two test cases in src/app/api/referrals/route.test.ts have expectations that don't match the current implementation in src/app/api/referrals/route.ts.

Bug 1 — Wrong success message expectation

Test (should create referrals for valid emails):

expect(body.message).toContain("1 invite(s) created and sent");

Actual code returns:

"1 invite(s) sent successfully"

The string "created and sent" never appears in the route's response.

Bug 2 — Wrong status code when all emails fail to deliver

Test (should keep created invites when email delivery fails):

expect(res.status).toBe(200);
expect(body.message).toContain("1 email(s) failed to send");

Actual code — when successfulEmails.length === 0 (all delivery failed):

return NextResponse.json(
  { error: "Failed to send invitation emails. Please try again." },
  { status: 502 }
);

The route returns 502, not 200. The message format is also different.

Steps to Reproduce

Run pnpm test src/app/api/referrals/route.test.ts — the two affected tests will fail.

Expected Fix

Update the test expectations to match the actual implementation:

1. Change "1 invite(s) created and sent" → "1 invite(s) sent successfully"
2. Update the email-failure test to expect 502 and check body.error contains "Failed to send" (reflecting the current emails-first, insert-on-success logic)

Tested

• Confirmed live: POST /api/referrals with a valid email returns "1 invite(s) sent successfully" (status 200)
• Confirmed live: duplicate invite returns 400 "All these emails have already been invited"