perf(portal): respond instantly after Omada auth, record session async

fix(portal): authorize via server-side omada-auth instead of browser redirect

Add captive portal free promo claims

Improve portal payment and success UX

Return vouchers to Omada for native auth

Validate portal vouchers through Omada

Update portal for Omada vouchers

Add portal auth timing logs and payment error handling

Fix portal auth session linking and admin alerts

Fix captive portal purchase throttling

improve phone input UX and fix migration crash safety

replace plan buttons with radio inputs for reliable selection

refactor captive portal: system font, customization wired in, UX fix

Initial commit — multi-tenant WiFi hotspot monetization platform