Current behavior: The 'Resend' dropdown item in billing-invoices-tab.tsx calls toast.info('Resend not yet implemented'). The router's resend mutation calls console.warn and returns success:true without sending anything. Past-due customers never get a reminder. Expected behavior: Clicking Resend immediately triggers the Resend email API with the invoice details, PDF attachment link, and payment CTA. Should work identically to the dunning emails already wired in billing-crons.ts. File: N/A Recommendation: Wire billing-invoices.ts resend mutation to call the same Resend API used in billing-crons.ts. Reuse buildEmailHtml from notifications.ts. Takes ~30 minutes.